SOIL  ALKALI 


WILEY      AGRICULTURAL       SERIES 

SOIL   ALKALI 

ITS  ORIGIN,  NATURE,  AND  TREATMENT 


BY 

FRANKLIN  STEWART  HARRIS,  PH.  D. 

DIRECTOR  AND  AGRONOMIST,    UTAH   AGRICULTURAL 

EXPERIMENT    STATION,   AND    PROFESSOR    OF   AGRONOMY 

UTAH  AGRICULTURAL   COLLEGE 


NEW  YORK 

JOHN  WILEY   &   SONS,   INC. 

LONDON:    CHAPMAN    AND    HALL,    LTD. 

1920 


COPYRIGHT • I92O • BY 
FRANKLIN     S.    HARRIS 


THE  PLIMPTON  PRESS   •   NORWOOD   •  MASS  •  U  •  S  •  A 


To 

DR.   JOHN   ANDREAS   WIDTSOE 

PIONEER-INVESTIGATOR    OF    ARID    AGRICULTURE,   TEACHER 
AND   FRIEND,    THIS    BOOK    IS    AFFECTIONATELY   DEDICATED 


PREFACE 

THE  study  of  soil  alkali  is  by  no  means  simple,  nor  have 
all  the  problems  relating  to  it  been  solved.  The  many 
different  salts  involved,  each  with  its  own  properties; 
the  various  types  of  soils  in  which  these  salts  occur,  all 
with  different  textures  and  composition;  the  complex 
relations  between  the  soluble  salts  of  the  soil  and  the  plants 
growing  on  it;  and  the  several  economic  factors  involved 
in  the  reclamation  of  alkali  land:  these  and  numerous 
other  considerations  make  the  problems  connected  with 
soil  alkali  as  difficult  to  solve  as  any  found  in  agricultural 
science. 

The  excuse  for  writing  a  book  on  a  problem  that  is  so 
far  from  solution  is  found  in  the  great  demand  that  exists 
for  one  volume  containing  the  important  information 
concerning  alkali.  At  present,  the  literature  of  the  sub- 
ject is  very  much  scattered  and  is  largely  unavailable  to 
the  average  student  of  soils. 

There  are  hundreds  of  millions  of  acres  of  land  in  the 
world  that  are  at  present  not  used  for  agriculture  but  which 
might  become  productive  if  the  alkali  could  be  eliminated. 
The  need  for  more  land  to  supply  food  for  the  world's 
increasing  population  is  making  a  very  insistent  demand 
that  some  of  these  alkali  lands  be  made  available.  The 
response  to  this  demand  will  depend  on  a  better  under- 
standing of  the  nature  of  alkali  and  methods  of  reclaiming 
land  impregnated  with  it.  This  accounts  for  the  new  in- 
terest that  is  being  shown  in  the  study  of  soil  alkali. 


viii  PREFACE 

The  present  volume  is  intended  as  a  text  and  reference 
work  for  students  of  soils  and  others  interested  in  arid 
agriculture.  It  should  find  wide  use  by  county  agricul- 
tural agents  and  the  better  trained  farmers  in  regions 
where  the  alkali  problem  is  encountered. 

References  are  given  in  connection  with  each  chapter. 
The  figures  in  parenthesis  in  the  body  of  the  text  indicate 
the  number  of  the  reference  at  the  end  of  the  chapter. 
No  attempt  has  been  made  to  cite  all  the  literature,  but 
most  of  the  important  papers  are  included.  Foreign  titles 
have  usually  been  translated  into  English  in  order  to  make 
them  clearer  to  the  general  reader.  Where  the  original 
article  is  likely  to  be  unavailable  an  attempt  has  been 
made  to  refer  to  an  abstract  in  some  available  publication 
such  as  the  Experiment  Station  Record. 

The  author  wishes  to  acknowledge  his  indebtedness  to 
all  who  have  contributed  either  directly  or  indirectly  to 
the  work.  He  has  drawn  freely  from  all  available  sources, 
but  he  is  particularly  indebted  to  Dr.  E.  W.  Hilgard  and 
his  associates  in  California  and  to  the  workers  in  the  Bureau 
of  Soils,  U.  S.  Department  of  Agriculture.  These  two 
sources  of  information  have  proved  to  be  veritable  "gold 
mines." 

The  following  who  have  read  part  or  all  of  the  manu- 
script have  given  many  valuable  suggestions:  Doctors 
J.  E.  Greaves,  E.  G.  Peterson,  F.  L.  West,  Willard  Gardner, 
and  G.  R.  Hill,  Jr.,  and  Professors  George  Stewart,  O.  W. 
Israelsen,  D.  W.  Pittman,  M.  D.  Thomas,  Mrs.  B.  C. 
Pittman,  and  Mr.  K.  B.  Sauls. 

The  author  also  wishes  to  express  his  appreciation  to 
the  several  assistants  and  co-workers  who  have  helped  in 
his  experiments  with  alkali  during  a  number  of  years. 
Without  the  faithful  and  efficient  services  of  these  men  the. 


PREFACE  ix 

experimental  work  which  led  up  to  this  book  could  not 
have  been  done.  Mr.  N.  I.  Butt  deserves  special  mention 
for  his  help  in  reviewing  literature  and  preparing  the 
material  of  this  book  for  publication. 

F.  %.  HARRIS 

LOGAN,  UTAH 
November  i,  1919 


CONTENTS 

CHAPTER  PAGE 

I.  INTRODUCTORY ...        3 

II.  GEOGRAPHICAL  DISTRIBUTION 6 

North    America.      Canada.      United    States.      Mexico.      South 
America.     Africa.*-  Egypt.     Europe.     Asia.     India.     Australia. 

III.  THE  ORIGIN  OF  ALKALI   16 

Composition    of    Soil-forming   Materials.      Salts    from    Ancient 
Seas.    Jurassic  Beds,  Montana.     Arms  of  the  Ocean.      Evapora- 
tion   of    Saline    Lakes.      Formation     of     Soluble     Carbonates. 
Nitrate  Formation.     Concentration  by  Irrigation  Water.     Rela- 
tion of  Origin  to  Methods  of  Treatment. 

IV.  NATURE  OF  ALKALI  INJURY  TO  THE  PLANT 34 

Prevention    of    Water    Absorption.     Effects    on    Germination. 
Effect  on  Structure  of  the  Plant.     Injury  at  the  Surface  of  the 
Soil. 

V.  Toxic  LIMITS  OF  ALKALI 42 

Toxicity  in  Solution.  Nutrient  Solutions.  Alkali  Solutions. 
Seed  Germination.  Seedling  Transference  into  Alkaline  Solu- 
tions. Soil  Results:  in  Sand,  in  Loam  Soil. 

VI.  NATIVE  VEGETATION  AS  AN  INDICATOR  OF  ALKALI 60 

How  Plants  Indicate  the  Soil.     Alkali-indicating  Plants:    Well- 
defined    Alkali-indicating    Plants,    Alkali-indicating    Plants    not 
Commonly  Forming  the  Major  Portion  of  Alkali-land  Vegeta- 
tion.    Discussion   of    Plants:     Inkweed    or    Salt- wort,    Tussock 
Grass  (Sporobolus  air  aides),    Kern  Greasewood  or  Bushy  Sam- 
phire    (Allenrolfea    occidentalis) ,    Dwarf    Samphire    (Salicornia 
subtermindis),    Greasewood    (Sarcobatus    vermiculatus) ,    Alkali- 
heath      (Frankenia    grand/alia     campenstris) ,      Cressa     (Cressa 
cretica    truxillensis) ,    Salt-bush    or    Shadscale    (Atriplex  spp.), 
Kochia  or  White  Sage  (Kochia  vestitd),     Salt-grass    (Distichlis 
spicata),  Other  Plants.     Description  of  Alkali-indicating  Plants. 

xi 


xii  CONTENTS 

CHAPTER  PAGE 

VII.  CHEMICAL  METHODS  OF  DETERMINING  ALKALI 81 

Preparing  the  Solution:    from  Moist  Soil,  from  Dry  Soil.     De- 
termining Total  Solids.     Carbonate  and  Bicarbonate  Determina- 
tion. Chloride  Determination.   Sulphate  Determination.   Nitrate 
Determination.     Analytical  Process.      Determination  of  Bases: 
Calcium,  Magnesium,  Sodium.     Other  Methods  of  Determining 
Soluble   Salts:    the   Electrical   Bridge,    Freezing-point   Method, 
Biological  Method. 

VIII.  CHEMICAL  EQUILIBRIUM  AND  ANTAGONISM 105 

Solubility  of  Alkali  Salts.  Mass  Action.  Absorption  of  Salts  by 
Soils.  Equilibrium  in  Soil  Solution.  Antagonism  between 
Alkali  Salts. 

IX.  RELATION  OF  ALKALI  TO  PHYSICAL  CONDITIONS  IN  THE  SOIL 119 

Changing  Soil  Structure.     Effect  of  Colloids.     Hardpan.     Effect 

on  Moisture  Movements.     Evaporation  of  Moisture. 

X.  RELATION  OF  ALKALI  TO  BIOLOGICAL  CONDITIONS  IN  THE  SOIL  .     132 
Relation  of  Soil  Organisms    to  Fertility.      Biological  Inactivity 

and  Soil  Sterility.  Concentrations  of  Alkali  which  Limit  Biolog- 
ical Activities. 

XI.  MOVEMENT  OF  SOLUBLE  SALTS  THROUGH  THE  SOIL 141 

Salts  in  Natural  Soils.     Salt  Movement  with  Water.     Effect  of 
Water-table.     Movement    of    Various    Salts.     Rate    of    Alkali 
Movement. 

XII.  METHODS  OF  RECLAIMING  ALKALI  LANDS 154 

The  Source  of  Contamination.     Reducing  Evaporation.     Plowing 
under  of  Surface  Alkali.     Removing  from  Surface.     Neutralizing 
Sodium    Carbonate.     Other    Chemical    Treatments.     Cropping 
with  Alkali-resistant  Crops.     Drainage. 

XIII.  PRACTICAL  DRAINAGE 167 

Advantages  of  Drainage.     Determining  the  Need  of  Drainage. 
Types  of  Drains.     Cement  Tile  for  Alkali  Land:    Preliminary 
Survey,  Laying  out  the  System,   Size  of  Drains,   Construction 
Methods.    Outlets  and  Silt  Basins.     Cost  of  Drainage. 

XIV.  CROPS  FOR  ALKALI  LAND 192 

Factors    Affecting     Resistance.     Economic     Factors     Affecting 
Choice.    Tolerance  of  Alkali  by  Various  Crops;    Forage  Crops, 


CONTENTS  xiii 

CHAPTER  PAGE 

XIV  (continued) 

Alfalfa,  Sweet  Clover  (Melilotus  alba  and  M.  officinalis) .  Other 
Clovers:  Vetch  (Vicia  saliva  and  V.  villosa),  Field  Peas  (Pisum 
satimim),  Beans.  Grasses:  Timothy,  Orchard  Grass  (Dactylis 
glomerata),  Brome  Grass  (Bromus  inermis),  Red  Top  (Agnostis 
alba},  Blueg  ass  (Poa  pratensis),  Western  Wheat  Grass  (Agropy- 
ron), Japanese  Wheat  Grass  (Agropyron  Japonicum)1.'Rye  Grass, 
Fescue,  Tall  Meadow  Oat-grass  (Arrlienatherum  elatins),  Wild 
or  Native  Grasses,  Salt  Grass  (Distichlis  spicata),  Bluestem  Grass 
(Agropyron  Occidental),  Tussock  Grass  or  Purple  Top  (Sporo- 
bolus  airoides),  Alkali  Meadow  Grass  (Puccinettia  airoides), 
Prairie  Grasses,— Modiola  (Modiola  procumbens) ,  Salt  Bushes 
(A  triplex  spp.),  Giant  Rye  Grass  (Elymus  condensatus) ,  Sedges 
and  Rushes,  Millets,  Sorghums,  Rape  (Brassica  napus  and  B. 
oleracea).  Grain  Crops:  Wheat,  Barley,  Oats,  Rye,  Corn,  Rice, 
Emmer,  Sunflowers.  Root  and  Vegetable  Crops:  Sugar-beets, 
Potatoes,  Onions,  Asparagus,  Celery,  Radishes,  other  Vegetables. 
Fiber  Crops:  Flax,  Cotton.  Trees  and  Shrubs:  Fruit  Trees  and 
Shrubs,  Date  Palms,  Grapes,  Olives,  Other  Fruits,  Other  Trees. 

XV.  ALKALI  WATER  FOR  IRRIGATION 224 

Sources   of   Contamination.    Observed   Toxic   Limits.     Compo- 
sition of  Typical  Alkali  Waters.     Factors  Modifying  Toxic  Limits 

of  Salt. 

XVI.  JUDGING  ALKALI  LAND 240 

Geology  of  Region.     General  Appearance.     Native  Vegetation. 
The  Water-table.     Analysis  of  the  Soil.     Possibility  of  Reclama- 
tion.   Economic  Factors. 

INDEX 247 


LIST   OF   ILLUSTRATIONS 

FIG.  PAGE 

Wheat  Raised  on  Reclaimed  Alkali  Land Frontispiece 

1.  Salt-bearing  Shale  Formation 24 

2.  Mancos  Shale  Hill 26 

3.  Normal  and  Plasmolyzed  Cells 35 

4.  An  Orchard  Planted  on  Land   that   Came  from  a 

Formation  High  in  Soluble  Salts 37 

5.  The  Lower  Part  of  an  Orchard  being  Killed  by  Alkali 

brought  to  the  Surface  by  a  Rising  Water  Table.  .       39 

6.  Experiments  to  Determine  the  Toxicity  of  Various 

Alkali  Salts 50 

7.  Growth  of  Wheat  with  Various   Concentrations  of 

Different  Salts 54 

8.  Alkali  Crusts  at  the  Surface  Preventing  the  Growth  of 

Practically  all  Vegetation 61 

9.  Alkali  Land  which  is  Indicated  by  the  Growth  of 

Shadscale 62 

10.  Greasewood  and  Shadscale 66 

11.  The  Border  between  Greasewood  and  Salt  Grass.  ...  68 

12.  The  Last  Plant  to  Abandon  an  Alkali  Flat 71 

13.  Plants  Growing  at  the  Top  of  Sand  Dunes 74 

14.  Determining  Soluble  Salts  with  the  Electric  Bridge 

in  the  Field 102 

15.  Alkali  Coming  to  the  Surface  where  Seepage  Water 

from  a  Canal  Comes  to  the  Surface  and  Evaporates    1 10 


xvi  ILLUSTRATIONS 

1 6.  Black  Alkali  Crust  Forming  where  the  Land  has  been 

Wet ' 115 

17.  Cultivated  Land  that  had  to  be  Abandoned  because 

of  the  Rise  of  Alkali 143 

18.  Alkali  Eating  away  the  Fence  Posts 147 

19.  Typical  Hard  Pan  Found  in  Arid  Soils 156 

20.  Field  Ready  for  Laying  Tile 168 

21.  Boggy  Alkali  Land  that  is  Difficult  to  Drain  with 

Short  Tile 171 

22.  Open  Ditch  used   to   Carry    away    the   Drainage 

Water  from  a  Large  Area 172 

23.  Machine  for  Making  Drains  in  Heavy  Soil  without 

the  Use  of  Tile 173 

24.  Poorly  Made   Cement   that  is  being  Crumbled  by 

Alkali 175 

25.  Method  of  Establishing  Grade  of  Drains 177 

26.  Types  of  Lumber  Drains  used  to  Reclaim  Boggy 

Alkali  Land 180 

27.  Wood  Drains  being  used  to  Drain  Boggy  Alkali  Land     184 

28.  Drainage    Machine    with    Digging     Wheel     above 

the   Ground 186 

29.  Drainage  Machine  with  Digging  Wheel  in  the  Trench     187 

30.  Silt  Box  with  Lid.     The  Silt  that  Settles  in  the  Box 

can  be  Spaded  Out 189 

31.  Alkali  Spot  in  a  Grain  Field 211 

32.  The  More  Tender  Trees  are  being  Killed  with  Rising 

Alkali,  while  Alfalfa  is  Still  Unaffected 227 

33.  Layer  of  Alkali  Several  Feet  below  the  Surface 241 


SOIL  ALKALI 


SOIL  ALKALI       , 

CHAPTER   I 
-  INTRODUCTORY 

WHENEVER  the  word  "  alkali  "  is  mentioned  there  im- 
mediately arises  in  the  minds  of  some  people  a  vision  of 
desolation.  They  may  picture  to  themselves  a  barren 
tract  of  land  devoid  of  vegetation  and  covered  with  a 
blanket  of  white  salt  mixed  with  earth;  or  they  may  fancy 
that  they  see  worthless  wastes  of  what  had  been  fertile 
fields.  They  imagine  beautiful  trees  being  reduced  to 
stumps  and  fence  posts  and  remnants  of  farm  buildings 
gradually  being  eaten  away  by  a  slowly  advancing  white 
cover,  which  will  eventually  reduce  the  entire  landscape 
to  a  gray  barrenness.  Probably  each  of  these  pictures 
has  a  prototype  in  some  local  section.  Alkali  does  prevent 
the  cultivation  of  vast  areas  of  land,  and  it  has  caused  the 
abandonment  of  many  fertile  fields;  but  to  give  up  all 
effort  when  alkali  makes  its  appearance  would  be  like 
abandoning  a  farm  just  because  some  crop  became  in- 
fested with  a  pest. 

The  successful  pursuit  of  agriculture  calls  for  the  con- 
stant overcoming  of  difficulties.  New  problems  arise 
each  season,  but  success  demands  that  these  be  solved. 
The  difference  between  civilization  and  savagery  consists 
largely  in  meeting  difficulties  and  being  masters  of  nature 
instead  of  merely  victims  of  circumstance. 

3 


4  INTRODUCTORY 

The  welfare  of  the  entire  people  is  dependent  on  the 
prosperity  of  agriculture,  and  in  turn  agriculture  rests  on 
the  productivity  of  the  soil.  Human  well-being  is  therefore 
closely  tied  up  with  the  land.  Whatever  affects  agricul- 
ture is  important  not  only  to  the  tillers  of  the  soil  but  to 
all  who  consume  the  products  of  the  farm.  In  order  that 
an  ample  food-supply  may  be  assured  at  a  low  price,  the 
people  generally  are  interested  in  having  available  as  large 
a  producing  area  as  possible. 

Most  of  the  more  desirable  lands  of  the  world  have  been 
settled.  This  means  that  an  extension  of  the  area  of  pro- 
duction will  often  necessitate  the  use  of  land  that  has 
some  unfavorable  condition.  There  are  in  the  world  vast 
tracts  that  are  not  susceptible  of  cultivation  without  special 
treatment.  In  the  arid  parts  of  the  earth,  which  comprise 
about  one-half  of  the  total  land,  two  great  conditions  are 
withholding  from  cultivation  millions  of  acres  of  land. 
They  are  drouth  and  alkali.  The  successful  overcoming 
of  drouth  and  alkali  means  the  addition  of  countless  acres 
to  the  productive  part  of  the  earth.  It  is  with  alkali 
and  its  conquest  that  the  present  volume  deals. 

It  has  been  estimated  that  about  13  per  cent  of  the 
irrigated  land  of  the  United  States  contains  sufficient 
alkali  to  be  harmful.  This  means  that  there  are  over 
nine  million  acres  of  land  under  present  canal  systems  that 
are  affected  with  alkali.  There  are  many  more  million 
acres  of  alkali  land  in  the  United  States  that  do  not  lie 
under  irrigation  systems.  Similar  figures  might  also  be 
given  for  other  countries  of  this  continent  and  for  all  of 
the  other  continents.  The  alkali  problem  is  one  of  no 
mean  importance  to  farmers,  nor  to  any  who  are  interested 
in  the  world's  food-supply. 

In  a  strictly  chemical  sense  the  word  "alkali "  refers 


INTRODUCTORY  5 

to  a  substance  having  a  basic  reaction.  As  applied  to  the 
soil,  however,  this  restricted  meaning  does  not  hold,  and 
alkali  refers  to  any  soluble  salts  that  make  the  soil  solution 
sufficiently  concentrated  to  injure  plants.  This  includes 
the  chlorides,  sulphates,  carbonates,  and  nitrates  of  sodium, 
potassium,  and  magnesium,  and  the  chloride  and  nitrate 
of  calcium.  The  sulphate  and  carbonate  of  calcium  are 
not  sufficiently  soluble  to  be  injurious  to  crops.  Most  of 
the  alkalies  are  in  reality  neutral  salts.  It  may  be  some- 
what unfortunate  to  use  for  general  substances  a  word  that 
also  has  a  restricted  technical  meaning,  but  the  word 
has  become  so  well  established  in  agricultural  literature 
that  it  would  now  be  very  difficult  to  change  it. 

Aside  from  their  practical  importance,  the  soluble  salts 
of  the  soil  are  of  great  scientific  interest.  They  offer 
fruitful  fields  for  investigation  to  the  geologist,  the  chemist, 
t^e  plant  physiologist,  the  bacteriologist,  the  mycologist, 
the  agronomist,  and  the  engineer.  The  complexity  of 
the  soil  makes  the  problems  connected  with  alkali  very 
difficult  to  solve.  There  are  so  many  interacting  factors 
that  no  simple  statement  of  the  problem  can  be  made 
and  no  simple  solution  arrived  at.  A  complete  under- 
standing of  the  problem  will  call  for  careful  researches  by 
investigators  in  different  branches  of  science  and  a  careful 
coordination  of  the  findings.  The  importance  of  the 
subject  justifies  giving  it  the  most  careful  consideration. 


CHAPTER  II 
GEOGRAPHICAL  DISTRIBUTION 

SOILS  containing  injurious  quantities  of  alkali  are  found 
on  every  continent.  These  soils,  however,  do  not  occur 
in  all  parts  of  the  continents,  the  distribution  being  con- 
fined to  areas  where  conditions  favorable  to  their  formation 
prevail.  The  most  important  of  these  conditions  is  aridity. 
Another  important  factor  is  the  nature  of  the  rock  from 
which  the  soils  were  formed.  Because  these  conditions 
are  local,  alkali  soils  are  likely  to  be  found  over  large  areas, 
but  all  the  soils  of  these  areas  are  not  necessarily  highly 
charged  with  soluble  salts.  Part  of  the  soils  in  a  region 
having  a  climate  favorable  to  alkali  formation  may  be 
derived  from  rocks  that  are  low  in  soluble  salts  and  may 
have  been  so  deposited  that  they  have  good  natural  drain- 
age. Soils  of  this  kind  do  not  contain  alkali  even  though 
most  of  the  soils  of  the  region  are  impregnated.  Likewise, 
soils  high  in  soluble  salts  may  be  found  over  limited  areas 
in  regions  where  most  of  the  soils  are  free.  This  condition 
is  sometimes  found  in  climates  that  are  not  entirely  arid, 
or  where  a  soil  having  poor  drainage  was  derived  from 
rock  that  was  high  in  soluble  salts.  Thus,  the  alkali 
problem  has  local  as  well  as  general  aspects.  A  general 
alkali  condition  may  prevail  over  en  extensive  region, 
the  smaller  areas  of  which  may  be  exceedingly  variable. 

North  America. —  More  than  half  of  the  North- Ameri- 
can continent  is  arid  or  semi-arid.  Throughout  this  vast 
area  alkali  soils  are  found.  There  are  many  large  tracts 

6 


CANADA  7 

in  which  the  soluble  salt  content  of  the  soil  is  not  at  present 
sufficient  to  interfere  with  crop  growth,  but  there  is  suffi- 
cient of  the  salts  present  if  concentrated  by  unwise  methods 
of  irrigation,  by  drouth,  or  by  other  means  to  bring  the 
soil  to  the  danger  point,  especially  should  drainage  be  poor. 

The  looth  meridian  may  be  taken  roughly  as  the  line 
separating  the  humid  from  the  arid  part  of  the  continent. 
This  line  is  not  absolute;  it  varies  somewhat  with  latitude, 
altitude,  and  several  other  factors.  There  are  a  number 
of  places  west  of  this  line  where  the  rainfall  is  high.  This 
is  particularly  true  along  the  northwest  coast  and  along 
some  of  the  mountain  ranges. 

Canada.  —  In  western  Canada,  especially  in  the  prov- 
inces of  Saskatchewan,  Alberta,  and  British  Columbia, 
there  are  several  rather  large  tracts  where  the  soluble- 
salt  content  of  the  soil  is  sufficiently  high  to  render  crop 
production  difficult.  In  southeastern  Alberta  the  soil  of 
one  of  these  regions  originated  from  the  glaciation  of  shale 
that  was  high  in  soluble  salts,  particularly  the  sulphates. 
Therefore,  sulphates  are  the  predominating  salt  of  the 
region.  The  soil  is  heavy  and  impervious;  consequently, 
there  has  been  very  little  movement  of  salts  from  its  original 
place  in  the  soils. 

Under  irrigation  these  salts  may  be  either  leached  down- 
ward or  brought  to  the  surface.  When  appearing  as  a 
white  inflorescence  they  are  very  conspicuous  and  would 
lead  the  casual  observer  to  believe  the  condition  to  be 
much  worse  than  it  really  is.  A  large  quantity  of  gypsum 
is  present  in  these  soils  and,  when  dissolved  and  brought 
to  the  surface,  it,  together  with  sodium  sulphate,  forms 
a  conspicuous  white  soil  covering.  Fortunately,  the 
percentage  of  the  more  harmful  chlorides  and  carbonates 
is  very  low. 


8 


GEOGRAPHICAL   DISTRIBUTION 


The  composition  of  an  alkali  soil  in  Alberta  as  determined 
by  Shutt  (16)  is  given  in  the  following  table. 


TABLE  I.    SOLUBLE  SALTS  IN  ALKALI  SOIL  or  ALBERTA,  CANADA 
(PER  CENT) 


Depth 
(feet) 

Growth 

Na2S04 

MgS04 

CaS04 

Total  Soluble- 
saline  Content 

0.0-0.5 

_ 

O-S-i-5 

Good 

.178 

.087 

-163 

.440 

1-5-3-0 

.877 

.132 

•447 

1-572 

3-o-S-o 

•973 

.563 

2.926 

4.640 

•?  o—  z  o 

Poor 

123 

.180 

o       o 

•  -1-  ^o 
.701 

.247 

.491 

.480 

.719 

•309 

-588 

,680 

•799 

.062 

.192 

.060 

3.0-5.0 

No 

1.741 

.900 

.648 

.260 

i  .001 

.323 

•364 

.700 

.701 

.222 

.220 

.  164 

•579 

.084 

.192 

.960 

United  States.  —  In  sixteen  or  seventeen  of  the  western 
states  of  the  Union,  alkali  is  found  to  be  one  of  the  chief 
agricultural  problems.  The  problem  is  much  more  acute 
in  some  regions  than  others.  The  San  Joaquin,  Sacra- 
mento, and  Imperial  Valleys  of  California;  the  Great 
Basin,  comprising  a  large  part  of  Utah  and  Nevada; 
the  Colorado  River  drainage  basin,  comprising  parts  of 
Wyoming,  Utah,  Colorado,  Arizona,  and  California; 
the  Rio  Grande  River  drainage  area,  including  parts  of 
New  Mexico  and  Texas;  parts  of  the  Columbia  River 
drainage  basin;  and  rather  extensive  sections  in  the  Great 
Plains  east  of  the  Rocky  Mountains  include  the  most 
important  parts  of  the  United  States  affected  with  alkali. 
In  practically  all  the  western  states  certain  areas  affected 
by  alkali  have  been  described  in  publications  of  the  state 


MEXICO 


experiment  stations  or  in  the  United  States  Bureau  of 
Soils.  (See  Table  II.)  These  publications  show  that  the 
composition  of  the  alkali  salts  as  well  as  the  methods  of 
reclamation  vary  greatly. 

TABLE  II.     COMPOSITION  OF  ALKALI  FROM  DIFFERENT  PARTS  OF 

THE  UNITCD  STATES  EXPRESSED  IN  PERCENTAGE  OF 

DIFFERENT  SALTS 


1  j 

Salts 

PERCENTAGE  OF  DIFFERENT  SALTS  IN  THE  ALKALI 

Coloradoi 

California2 

Washing- 
•  ton" 

Montana4 

Arizona5 

Crust 

Surface, 
10  in. 

Crust 

0-7  2  in. 

KC1  
K2SO4  

1.64 

3-95 

25.28 
19.78 
32.58 
14-75 
2.25 

5-6l 
9-73 

1.  60 

21.41 

4.00 

22.  IO 

K2CO3  
NaoS04  
NaNO3 

33-0? 
6.61 

85-57 

35-12 

Na2C03  
NaCl 

13.86 

o-55 
8.90 

7.28 
4.06 

81.15 

7.71 
0.25 
0.28 
6.61 

13-77 

6!88 
3-98 

21  .02 
32.25 

Na3HPO4.  . 

MgSO4.  .  . 

MgCl2  
CaCl2 

12.71 
17.29 

21.48 

NaHCO3... 
CaSO4  

36.72 
1.87 
16.48 
It   72 

0.67 
2.71 

22.06 
10.07 

Ca(HCO3)2 

Mg(HC03)2.  .  . 
(NH4)2C03.... 

1.41 

Mexico.  —  The  greater  part  of  the  high  plateau  of 
Mexico  has  an  arid  climate.  This,  like  all  similar  regions, 
has  had  but  comparatively  little  of  the  soluble  salts 
contained  in  the  country  rock  removed.  In  this  section 
there. are  many  large  valleys  having  no  outlets.  During 

1  Colorado  Exp.  Sta.,  Bui.  155,  p.  10. 

2  Hilgard"Soils,"p.  442. 

3  U.  S.  D.  A.  Bur.  Soils,  Bui.  35,  p.  79. 

4  U.  S.  D.  A.  Bur.  Soils,  Bui.  35,  p.  103. 
6  U.  S.  D.  A.  Bur.  Soils,  Bui.  35,  p.  109. 


10  GEOGRAPHICAL  DISTRIBUTION 

the  rainy  season  the  lower  parts  of  these  valleys  are  flooded 
by  the  waters  of  swollen  streams;  during  the  dry  season 
this  water  is  practically  all  evaporated,  leaving  its  soluble 
material  behind.  This  results  in  great  level  bodies  of 
land  charged  in  varying  degrees  with  soluble  salts.  The 
composition  of  these  saline  deposits  depends  on  the  com- 
position of  the  country  rock  through  which  the  streams 
flow.  Very  little  work  up  to  the  present  time  has  been 
done  to  reclaim  the  alkali  soils  of  Mexico. 

South  America. —  No  important  published  material  is 
available  on  the  alkali  condition  of  the  soils  of  South 
America.  It  is  known,  however,  that  the  arid  sections  of 
that  continent  do  not  differ  essentially  from  those  of  other 
arid  sections  of  the  world.  Practically  the  entire  western 
part  of  the  continent  is  arid  and  throughout  this  section 
areas  subject  to  alkali  troubles  are  found.  It  includes 
most  of  the  Pacific  slope  west  of  the  Andes  and  the  greater 
part  of  the  western  plains  of  Brazil  and  Argentina  east  of 
these  mountains. 

The  deposits  of  sodium  nitrate  in  Chile  are  a  conspicuous 
example  of  the  retention  of  soluble  salts  that  would  be 
leached  out  in  a  humid  climate. 

Africa.  —  The  distribution  of  alkali  soils  in  Africa  is  not 
the  same  as  in  North  and  South  America.  It  is  found 
over  practically  the  entire  northern  portion  of  the  con- 
tinent and  also  in  the  southwestern  part.  The  central, 
and  particularly  the  west-central,  portion  is  practically 
free.  Throughout  the  Union  of  South  Africa  up  into 
Rhodesia  alkali  soils  are  found  but  have  not  received  as 
much  attention  as  some  of  the  sections  of  North  Africa, 
particularly  in  Egypt.  The  soils  of  the  Sahara  as  well  as 
many  of  those  of  Algeria,  Morocco,  and  Tunis  are  so 
contaminated  with  soluble  salts  that  it  was  necessary  for 


EGYPT  11 

the  agriculture  of  these  countries  to  be  adjusted  to  this 
condition.  It  is  probable  that  the  alkali  problem  is  being 
given  more  consideration  in  Egypt  than  elsewhere. 

Egypt.- —  The  greater  part  of  Egypt  is  a  barren  desert, 
being  one  of  the  most  desolate  parts  of  the  earth.  The  an- 
nual precipitation  at  Alexandria  averages  8.26  inches; 
at  Port  Said,  3.49  inches;  and  at  Cairo  it  is  only  1.06 
inches,  which  is  not  enough  to  support  vegetation  of  any 
kind.  The  country  is  traversed  from  south  to  north  by  the 
Nile  River  along  which  is  a  narrow,  highly  cultivated,  and 
thickly  populated  strip  of  river-formed  land.  In  the 
southern  part  of  the  country  the  river  flows  through  sand- 
stone and  occupies  a  shallow  valley,  but  farther  north  a 
deep  gorge  is  cut  down  from  the  surrounding  limestone 
plateau.  On  both  sides  of  the  river  are  alluvial  plains 
composed  of  fine  silt  which  for  the  most  part  has  been 
carried  by  the  Nile  from  the  disintegrated  volcanic  material 
of  the  Abyssinian  highlands.  Thus  the  soil  of  the  lower 
Nile  Valley  bears  no  relation  to  the  country  rock  of  the 
immediate  vicinity. 

In  the  delta  portion  of  the  valley,  the  land  is  very  flat 
and  there  is  but  little  opportunity  for  drainage.  Much 
land  that  was  cultivated  anciently  has  since  been  abandoned 
on  account  of  the  accumulation  of  alkali.  The  area  thus 
abandoned  has  been  estimated  to  be  more  than  one  and 
a  half  million  acres.  Most  of  this  land  is  on  the  fringe 
that  borders  the  sea  and  is  influenced  by  sea  water.  The 
higher  lands  are  practically  free  from  alkali. 

Formerly  all  the  land  was  watered  by  the  basin  system 
of  irrigation.  With  this  method,  the  land  is  flooded  to  a 
depth  of  from  three  to  five  feet  at  the  season  when  the  Nile 
is  high.  After  standing  at  this  depth  for  about  six  weeks 
and  allowing  the  sediment  to  settle,  the  water  is  drained 


12 


GEOGRAPHICAL  DISTRIBUTION 


back  into  the  Nile,  and  the  crops  are  planted  in  the  mud 
without  plowing.  By  this  system  only  one  crop  is  grown 
each  year,  but  the  accumulation  of  alkali  is  prevented  by 
washing  part  of  it  to  lower  depths  in  the  soil,  by  depositing 
a  fresh  layer  of  salt-free  silt  on  the  surface,  and  by  carrying 
away  with  the  water  that  is  drained  off  any  soluble  material 
that  may  have  accumulated  on  the  surface  at  the  time  of 
flooding. 

In  order  to  raise  more  than  one  crop  a  year  and  thereby 
get  greater  profit  from  the  land,  the  basin  system  of  irri- 
gation is  being  largely  supplanted  by  the  perennial  system, 
by  means  of  which  water  is  applied  throughout  the  year. 
This  brings  about  almost  continuous  evaporation  from  the 
surface  and  a  consequent  accumulation  of  soluble  salts. 
Of  the  6,250,000  acres  of  irrigable  land  in  Egypt,  only 
about  1,730,000  acres  are  irrigated  by  the  old  system  of 
basin  irrigation.  This  means  that  the  alkali  problem 
will  continue  to  be  more  acute  in  Egypt  until  suitable  means 
of  coping  with  it  are  worked  out.  Already  some  rather 
ingenious  methods  (23,  25)  of  drainage  are  in  operation. 

The  following  analysis  reported  by  Means  (14)  of  an 
alkali  soil  from  Kom-el-Akhdar  is  typical  of  the  alkali 
land  of  lower  Egypt: 

TABLE  III.     CHEMICAL  ANALYSIS  OF  ALKALI  SOIL  FROM  KOM-EL- 
AKHDAR,  EGYPT  (Surface  foot) 


Ions 

Per  cent 

Conventional  Combinations 

Percent 

Calcium  (Ca)  
Magnesium  (Mg)  
Sodium  (Na)  
Potassium  (K)  
Sulphuric  Acid  (804)  .... 
Chlorine  (Cl)  

3-0? 
2.OO 
28.83 
I.QO 
24.56 
38.62 

Calcium  Sulphate  (CaSO4)  .... 
Magnesium  Sulphate  (MgSO4) 
Potassium  Chloride  (KC1)  
Sodium  Chloride  (NaCl)  
Sodium  Bicarbonate  (NaHCO3) 
Sodium  Sulphate  (NauSCM  .... 

iQ-43 

9.90 

3.62 
60.88 
1.41 
13.76 

Bicarbonate  Acid  (HCO3) 

I  .02 

Per  cent  Soluble. 

8.2 

INDIA  13 

Europe. —  Of  all  the  continents,  Europe  is  the  most 
free  from  alkali,  although  it  has  several  alkali  sections. 
Probably  the  most  conspicuous  of  these  is  found  in  Hun- 
gary. The  "Szik  "  lands  of  the  plains  contain  some  soluble 
salts  and  lower  down  in  the  valley  of  the  Theiss  genuine 
alkali  lands  are_  found  with  a  high  content  of  both  white 
and  black  alkali.  From  these  lands  carbonate  of  soda 
has  long  been  obtained  commercially.  In  the  lower 
valley  of  the  Po  in  Italy  (2)  and  in  many  other  sections 
of  Europe  bordering  the  Mediterranean  local  alkali  areas 
are  found. 

Asia.  —  The  main  alkali  regions  of  Asia  are  found  in 
the  central  and  southwestern  portions  of  the  continent. 
Arabia,  Mesopotamia,  Persia,  Afghanistan,  Baluchistan, 
Turkestan,  and  Northern  India  are  all  more  or  less  affected 
with  alkali  salts.  In  some  of  these  countries  agriculture 
has  continued  in  spite  of  the  excess  of  soluble  salts  because 
special  methods  have  been  devised  as  a  result  of  experience 
extending  back  to  prehistoric  times. 

Modern  investigations  of  alkali  have  been  more  complete 
in  India  than  in  other  parts  of  Asia;  consequently,  more 
attention  will  be  given  to  that  country  in  the  present 
discussion. 

India.  —  The  alkali,  or  reh,  lands  of  India  were  first 
investigated  by  the  "Reh  Commission "  about  1876. 
This  commission  was  appointed  to  discover  the  cause  of 
deterioration  of  some  of  the  lands  that  had  previously  been 
fertile.  Since  that  time  the  various  experiment  stations 
in  India  have  made  more  extensive  investigations.  They 
have  shown  that  "usar"  lands  (12)  exist  largely  not  only 
in  the  northwestern  provinces  and  Oudh,  but  also  in  the 
Punjab,  especially  on  lands  bordering  the  Chenab  River, 
likewise  to  a  slight  extent  in  the  Bombay  Presidency. 


14  GEOGRAPHICAL  DISTRIBUTION 

The  Reh  Commission  brought  out  the  fact  that  under 
the  ancient  systems  of  agriculture  in  India  there  was  very 
little  increase  in  the  amount  of  soluble  salts  at  the  surface, 
but  with  the  construction  of  large  modern  canals  and  the 
application  of  unnecessarily  large  quantities  of  irrigation 
water  the  increase  in  alkali  was  very  rapid. 

Leather  (12)  has  pointed  out  that  not  all  the  lands  called 
by  the  natives  "usar  "  owe  their  infertility  to  alkali.  Some 
simply  have  very  hard  clay  soils  which  are  difficult  to 
bring  into  a  good  state  of  tilth.  The  true  "reh"  lands, 
however,  are  like  the  alkali  lands  of  other  parts  of  the 
world. 

Australia.  —  The  greater  part  of  Australia  may  be  con- 
sidered as  arid  although  the  rainfall  of  the  eastern  part  of 
the  continent  is  high.  During  the  last  generation  large 
irrigation  works  have  been  constructed  and  vast  tracts  of 
land  containing  a  rather  high  content  of  soluble  salts  have 
been  brought  under  cultivation.  In  such  sections  alkali 
is  one  of  the  serious  problems.  Alkali  conditions  in  Aus- 
tralia are  somewhat  similar  to  those  of  the  western  part  of 
the  United  States. 


REFERENCES 

1.  AMES,  J.  W.     Some  Alkali  Soils  in  Ohio.    Ohio  Sta.  Mo.  Bui.  i  (1916), 

No.  7,  pp.  209-210. 

2.  ATTI,  R.     A  Saline  Soil  of  the  Lower  Valley  of  the  Po  (Italy).     Accad. 

Econ.  Agr.  Firenze,  5,  Ser.  3  (1906),  No.  i,  pp.  59-64.     (Abs.  E.  S. 
R.  18,  p.  215.) 

3.  BANCROFT,  R.   L.     The  Alkali  Soils  of  Iowa.     Iowa  Sta.   Bui.    177 

(1918),  pp.  185,  208. 

4.  BURD,  J.  S.     Alkali  Conditions  in  the  Payette  Valley.     Idaho  Sta. 

Bui.  51  (1905),  pp.  1-20. 

5.  CLARKE,  F.  W.    The  Data  of  Geochemistry.     U.   S.  Geol.  Survey, 

Bui.  616  (1916),  pp.  143-167  and  206-247. 

6.  DEAKIN,  ALFRED.     Irrigated  India,  322  pp.     (London,  1893.) 


REFERENCES  15 

7.  DIMO,  N.  A.     Influence  of  Irrigation  and  of  Increased  Natural  Hu- 

midity on  the  Process  of  Salt  Formation  and  of  the  Transportation 
of  Salts  in  the  Soils  and  Subsoils  of  Golodnoi  (Hungary)  Steppe, 
Smarkand  Province.  Russ.  Jour.  Exp.  Landw.  15  (1914),  No.  2, 
PP.  336-338.  (Abs.  E.  S.  R.  34,  p.  16.) 

8.  HEBERT,  A.     Alkali  Soils   from  the  Knee  of  the  Niger  River.     Bui. 

Soc.  Chim.,  France,  4,  Ser.  9  (1911),  Nos.  16,  17,  pp..  842-843. 

9.  HILGARD,  E.  W.     Soils,  pp.  423-424.     (New  York,  1906.) 

10.  HILL,  E.  G.  The  Analysis  of  Reh,  the  Alkali  Salts  in  Indian  Usar 
Land.  Proc.  Chem.  Soc.,  London,  19  (1903),  No.  262,  pp.  58—61. 
(Abs.  E.  S.  R.  14,  p.  1056.) 

u.  KEARNEY,  T.  H.,  and  MEANS,  T.  H.  Crops  Used  in  the  Reclamation  of 
Alkali  Lands  in  Egypt.  U.  S.  D.  A.  Yearbook  (1902),  pp.  573-588. 

12.  LEATHER,  J.  W.     Investigation  of  Usar  Land  in  the  United  Provinces, 

Allahabad,  India.     Govt.,  1914,  pp.  88.     (E.  S.  R.  33,  p.  419.) 

13.  MANN,  H.  H.,  and  TAMHANE,  V.  A.     The  Salt  Lands  of  the  Nira  Valley 

(India).     Dept.  of  Agr.,  Bombay,  Bui.  39,  35  pp. 

14.  MEANS,  T.  H.     Reclamation  of  Alkali  Lands  in  Egypt.     U.  S.  D.  A. 

Bur.  of  Soils,  Bui.  21  (1903),  48  pp. 

15.  MACOWAN,  P.     Black  Land  in  Relation  to  Irrigation  and   Drainage, 

Agr.  Jour.  Cape  Good  Hope,  23  (1903),  No.  5,  pp.  573-581. 

16.  SHUTT,  F.  T.   and  Smith,  E.  A.     The  Alkali   Content  of  Soils  as 

Related  to  Crop  Growth.  Trans.  Roy.  Soc.  Can.  Ser.  3  (1918), 
Vol.  12,  pp.  83-97. 

17.  SIGMOND,  A.  VON.     On  the  Types  of  "Szik"  Soils  of  the  Hungarian 

Alfold.  Foldtani  Kozlony,  36  (1906),  No.  10-12,  pp.  439-454. 
(Abs.  E.  S.  R.  19,  p.  1117.) 

18.  SNOW,  F.  J.,  HILGARD.  E.  W.,  and  SHAW,  G.  W.    Lands  of  the  Colorado 

Delta  in  the  Salton  Basin.     Cal.  Sta.  Bui.  140  (1902),  pp.  51. 

19.  STEVENSON,  W.  H.,  and  BROWN,  P.  E.    Improving  Iowa's  Peat  and 

Alkali  Soils.     Iowa  Sta.  Bui.   157   (1915),  pp.  45-79. 

20.  TRAPHAGEN,  F.  W.    The  Alkali  Soils  of  Montana.     Mont.  Sta.  Bui.  18 

(1898),  pp.  50. 

21.  TULAIKOV,  N.     Soils  of  the  Kirghiz  Steppe.     Russ.  Jour.  Exp.  Landw. 

9  (1908),  pp.  628-630.     (Abs.  E.  S.  R.  22,  p.  617.) 

22.  VISSOTSKI,   G.    The  Soil  Zones  of  European    Russia  in   Connection 

with  the  Salt  Content  of  the  Subsoils  and  with  the  Character  of  the 
Forest  Vegetation.  Pochvovedenie  (Pedologie),  i  (1899),  pp. 
19-26.  (Abs.  E.  S.  R.  12,  p.  925.) 

23.  WILLCOCKS,   W.     Egyptian   Irrigation,   485   pp.     (London   and    New 

York,  1899.) 

24.  WILLCOCKS,  W.     The  Irrigation  of  Mesopotamia.     (London  and  New 

York,  1911.) 

25.  WILLCOCKS,  W.     The  Nile  in  1904,  225  pp.     (London,  1904.) 


CHAPTER    in 


THE   ORIGIN   OF  ALKALI 

THE  presence  of  alkali  incrustations  over  the  surface  of 
the  soil  was  observed  long  before  scientists  were  able  to 
account  for  the  origin  of  these  salts.  This  led  to  quite 
a  number  of  theories  regarding  the  source  of  the  alkali. 
Several  of  the  early  theories  have  been  found  untenable 
in  the  light  of  later  investigation.  Many  of  the  formerly 
obscure  facts  are  now  definitely  known  and  there  is  a  much 
clearer  idea  of  the  source  of  the  soluble  salts  of  the  soil; 
but  even  today  considerable  difference  of  opinion  exists 
regarding  the  origin  of  some  of  these  salts.  More  data 
must  be  gathered  before  it  will  be  possible  to  state  definitely 
why  certain  deposits  of  alkali  occupy  their  present  position 
and  maintain  their  present  composition.  It  is  definitely 
known  that  there  are  a  number  of  distinct  conditions 
promoting  the  accumulations  of  alkali  in  various  sections. 

TABLE  IV.    AVERAGE  COMPOSITION  OF  IGNEOUS  ROCKS,  SHALE, 
AND  SANDSTONE  (PER  CENT) 


Igneous  Rocks 

Shale 

Sandstone 

Quartz 

12   O 

22    •? 

66.8 

Feldspar  

59.5 

3O.O 

11.5 

Hornblende  and  pyroxene.  .  .  . 
Mica 

16.8 
3  8 

Clay..  
Limonite 

25.0 
e   6 

6.6 

i  8 

Carbonates       .  . 

c  .  7 

ii  .  i 

Other  minerals  

7-9 

11.4 

2.2 

COMPOSITION  OF   SOIL-FORMING  MATERIALS     17 


Composition  of  Soil-forming  Materials.  There  seems 
to  be  no  doubt  that  the  soluble  salts  of  the  soils  have  come 
from  the  same  materials  as  the  soils.  The  exact  chemical 
reactions  that  have  brought  about  these  changes  and  the 
methods  of  concentrating  the  soluble  constituents  are, 
however,  not_so  well  known.  The  materials  composing 
the  soil  have  been  derived  largely  from  the  rocks  and 
minerals  which  constitute  the  crust  of  the  earth,  together 
with  a  greater  or  lesser  quantity  of  organic  matter  coming 
from  the  dead  bod  ies  of  plants. 

TABLE  V.    AVERAGE  COMPOSITION  OF  THE  LITHOSPHERE 


Igneous 
(05  per  cent) 

Shale 
(4  per  cent> 

Sandstone 
(0.75  per 
cent) 

Limestone 
(0.25  per 
cent) 

Weighted 
Average 

Si02.. 
A1203  
FoOi 

59-83 
14-98 
2    6? 

58.10 
15-40 
4.   O2 

78.33 
4-77 
I   07 

5-19 
.81 

CA 

59-77 
14-89 

2    69 

FeO...:.... 
MgO  
CaO  
Na20  
K2O  
H2O  
TiOs  
ZrO2 

3-46 

3.81 
4.84 
3.36 

2.99 
1.89 
.78 

02 

2-45 

2-44 
3-ii 
1.30 

3-24 
5-oo 
.65 

•30 
1.16 
5-50 
•45 
i-3i 
1.63 
•25 

"7^9 
42-57 
•05 

•33 
•77 
.06 

3-39 
3-74 
4.86 

3-25 
2.98 

2.02 

•77 
02 

CO2  

.48 

2.63 

5.03 

41  .  $4. 

70 

F205  
S  
SO3  

29 

.11 

•17 
.64 

.08 
07 

.04 
.09 
oc 

.28 
.10 
02 

Cl  

.06 

02 

06 

1<\  

BaO  
SrO. 

.  IO 
.10 
04 

•05 

•05 

.09 
.09 

OA. 

MnO 

.  IO 

oc 

OO 

NiO     

.O2< 

O2S 

Cr2O3  

•  OS 

oc 

V203  
Li2O 

.025 
OI 

•025 

C 

80 

•°3 

100.000 

100.00 

IOO.OO 

IOO.OO 

100.000 

18 


THE  ORIGIN  OF  ALKALI 


Compilations  made  by  Clarke  (6)  show  the  earth's 
crust  to  be  made  up  largely  of  the  important  minerals 
shown  in  Table  IV  (page  16). 

On  the  basis  of  the  composition  and  relative  amount  of 
the  different  rocks  he  computes  the  average  composition 
of  the  earth's  crust  as  shown  in  Table  V  (page  17). 

Clarke  (6)  gives  the  composition  of  the  ocean  waters 
as  follows: 

TABLE  VI.    COMPOSITION  OF  OCEAN  WATER 


Salts 

Per  cent 

Elements 

Per  cent 

Sodium  Chloride  (NaCl)  

77.76 

Oxygen  

85-79 

Magnesium  Chloride  (MgC^)  .  .  . 

10.88 

Hydrogen.  .  .  . 

10.67 

Miagnesium  Sulphate  (MgSO4) 

474 

Chlorine.  . 

2    O7 

Calcium  Sulphate  (CaSO4)  

3-60 

Sodium  

I.I4 

Potassium  Sulphate  (K2SO4)  .... 

2.46 

Magnesium.  .  . 

.14 

Magnesium  Bromide  (MgBr^)  .  .  . 

.  22 

Calcium  

•05 

Calcium  Carbonate  (CaCO3)  

•34 

Potassium.  .  .  . 

.04 

Sulphur  

.09 

Bromine  

.008 

Carbon  

.002 

100  .  OO 

IOO.OO 

He  reports  a  maximum  salinity  of  37.37  grams  of  salts 
to  a  kilogram  of  water,  or  3.737  per  cent  with  an  average 
of  about  3.5  per  cent. 

These  figures  give  a  general  idea  of  the  materials  from 
which  soils  are  made  and  the  substances  which  have  been 
leached  from  them. 

In  order  to  determine  soluble  matter  that  might  be 
washed  from  rocks  and  minerals  of  various  kinds,  Whitney 
and  Means  (23)  compiled  the  material  contained  in  Table 
VII  from  the  writings  of  G.  P.  Merrill. 

This  table  gives  an  idea  of  the  material  that  is  usually 
washed  from  rocks  and  minerals  of  different  kinds  in  the 


COMPOSITION  OF   SOIL-FORMING   MATERIALS     19 


TABLE  VII.     AMOUNT  or  SOLUBLE  MATTER  REMOVED  IN  THE 
DECOMPOSITION  or  ROCKS  AND  THE  FORMATION  or  SOILS 


ROCK  REMOVED  BY  SOLU- 

TION FROM  EACH  ACRE- 

Kind  of  Rock 

Locality 

FOOT  OF  SOIL  FORMED 

Per  cenf 

Tons 

Granite 

District  of  Columbia 

*3 

26l 

Gneiss 

Virginia 

45 

1,431 

Syenite 
Phenolite 

Arkansas 
Bohemia 

56 

IO 

2,227 

J9S 

Diabase 

Massachusetts 

15 

309 

Diabase 

Venezuela 

40 

1,166 

Basalt 

Bohemia 

44 

i,376 

Basalt 

France 

60 

2,625 

Diorite 

Virginia 

38 

1,072 

Soapstone 

Maryland 

52 

1,895 

Soapstone 

Virginia 

78 

6,204 

Limestone 

Arkansas 

98 

85,760 

formation  of  soils.  Dissolved  material  may  be  washed 
to  the  sea  or  into  lakes,  or  it  may  simply  be  transferred  to 
lower  lying  soil  and  there  often  concentrated  so  highly 
that  it  becomes  injurious  to  plant  growth.  Some  of  these 
dissolved  materials,  such  as  limestone,  are  not  sufficiently 
soluble  to  be  troublesome  even  in  the  highest  possible 
concentrations. 


TABLE  VIII. 


PERCENTAGE  OF  ALKALIES  IN  VARIOUS  SOIL- 
FORMING  MINERALS 


Feldspars 

Per  cent 
of  Alkalies 

Micas 

Per  cent 
of  Alkalies 

Orthoclase  

17 

Muscovite  

12 

Microline  . 

1  7 

Biotite 

IO 

Albite  

12 

Phlogopite  

9 

Olioclase.  .  . 

Nepheline.  .  . 

24 

Andesite  

8 

Leucite 

21    S 

Labradonte  

4 

Sodalite  ... 

26 

Bytownite  

7  .  C 

Haiiyne  

17 

Anorthite  .    .  • 

2 

20  THE  ORIGIN  OF  ALKALI 

The  same  authors  (23)  give  a  list  of  alkali-bearing  min- 
erals occurring  in  primary  rocks  as  the  ultimate  source 
of  soil  alkali. 

"Some  of  these  alkali-bearing  minerals  are  very  generally 
present  in  the  primary  rocks  from  which  the  soils  have  all 
ultimately  been  derived,  but  they  are  of  course  usually 
mixed  with  other-  minerals,  so  that  the  total  percentage  of 
alkalies  in  the  rock  is  not  so  great  as  would  appear  from 
these  minerals." 

As  to  the  method  of  separating  these  soluble  substances 
and  transferring  them  to  the  surface,  Cameron  suggested 
a  hypothesis  which  is  quoted  by  Dorsey  (7)  as  follows: 

"The  major  part  of  the  complex  crystalline  masses  or 
of  rocks  forming  the  earth's  crust  contain  chlorine  and 
sulphur.  F.  W.  Clarke  gives  as  an  average  0.07  per  cent 
chlorine  and  0.108  per  cent  sulphur.  As  a  result  of  the 
hydrolyzing  action  of  water  and  other  decomposing  agencies 
probably  all  the  chlorine  and  very  much  of  the  sulphur 
is  converted  into  hydrochloric  acid  and  sulphuric  acid, 
which  in  turn  form  the  corresponding  salts  of  the  alkalies 
and  alkaline  earths.  The  aggregate  amount  which  is 
thus  being  constantly  formed  in  the  subsoils  and  under- 
lying strata  of  any  one  area  must  be  very  large.  As 
evaporation  proceeds  at  or  in  the  surface  soil,  there  is  a 
rise  of  the  water  in  the  underlying  layers  through  the 
capillary  spaces  toward  the  surface,  bringing  with  it  the 
hydrochloric  and  sulphuric  acids  or  their  salts. 

"The  sulphuric  acid  moves  up  more  slowly  than  does 
the  hydrochloric  acid;  partly,  perhaps,  because  the  rock 
masses  and  the  soils  have  a  greater  absorbing  action  on 
sulphuric  than  on  hydrochloric  acid,  tending  to  withdraw 
it  from  solution;  partly,  perhaps,  because  reducing  con- 
ditions may  exist  on  some  layers  tending  to  the  formation 


COMPOSITION  OF  SOIL-FORMING  MATERIALS     21 

of  metallic  sulphides;  and,  partly,  undoubtedly,  to  the 
formation  of  the  slightly  soluble  calcium-  sulphate.  This 
last,  however,  is  gradually  brought  toward  the  surface, 
and  is  often  found  in  enormous  masses  at  moderate  depths 
in  the  soils  of  arid  regions.  Undoubtedly  the  calcium 
carbonate  so  generally  found  in  large  masses  at  moderate 
depths  in  the  soil  of  arid  regions  originates  in  a  similar 
manner. 

"  Hydrochloric  acid  is  transported  through  soils  and 
most  absorbing  media  with  comparative  ease.  Moreover 
the  chlorides  of  the  alkalies  and  alkaline  earths  are  readily 
soluble.  Chlorides  should  be  expected,  therefore,  to 
accumulate  in  preponderant  masses  at  the  surface,  which 
under  arid  and  semi-arid  conditions  they  generally  do. 

"The  preponderance  of  sodium  chloride  above  other 
chlorides  is  readily  explicable.  It  is  well  known  that  when 
solutions  of  chlorides  are  poured  through  columns  of  soil 
or  similar  substances,  offering  a  large  surface  of  contact 
to  the  solution,  there  is  a  well-marked  selective  absorption, 
the  soil  tending  to  withdraw  the  base  from  the  solution 
to  a  decidedly  greater  extent  than  the  acid,  with  the  result 
that  the  leaching  generally  contains  free  acid.  So  far  as 
the  experience  we  have  goes,  it  would  seem  that,  in  general, 
soils  absorb  potassium  most  readily,  then  magnesium, 
calcium,  and  sodium  in  the  order  named.  Supposing  the 
hydrochloric  acid  when  found  in  the  lower  layers  to  be 
neutralized  with  a  mixture  of  these  bases,  as  it  rises  in  the 
capillary  movement,  there  is  always  a  tendency,  owing  to 
the  selective  absorption  of  the  soil,  toward  a  lagging 
behind  of  the  potassium,  a  lesser  lagging  of  the  magnesium 
and  calcium  (these  bases  probably  tending  also  to  form 
the  much  less  soluble  sulphates  and  carbonates)  and  a 
much  less  lagging  of  the  sodium.  In  consequence,  sodium 


22  THE  ORIGIN  OF  ALKALI 

is  the  predominating  base  in  the  readily  soluble  salts  at 
the  surface." 

This  hypothesis  does  not  explain  the  method  of  accumu- 
lation of  alkali  at  certain  places  in  the  soil;  it  merely 
attempts  to  show  why  certain  salts  are  present  at  the  sur- 
face in  larger  quantities  than  others. 

Salts  from  Ancient  Seas.  —  The  observation  that  alkali 
is  found  in  large  quantities  in  one  section,  whereas  it 
may  be  almost  entirely  lacking  in  another  section  of  sim- 
ilar climatic  conditions  early  led  to  an  attempt  to  trace 
the  salt  to  the  rock  from  which  the  soil  was  formed. 
Traphagen  (21),  at  the  suggestion  of  W.  H.  Weed  of  the 
U.  S.  Geological  Survey,  made  a  comparison  of  the  composi- 
tion of  the  alkali  near  Billings,  Montana,  with  the  soluble 
salts  in  the  Fort  Ben  ton  shales  from  which  the  soils  were 
in  part  derived.  As  a  result  of  this  study  he  was  led  to 
the  conclusion  that  in  this  case  the  soluble  salts  in  the  soil 
resulted  from  a  transference  of  the  salts  to  the  soil  while 
the  shale  was  being  disintegrated.  This  theory  was 
afterward  supported  by  the  work  of  Whitney  and  Means 
(23)  in  the  same  region.  Cameron  (4)  also  mentions  shale 
and  similar  deposits  as  a  source  of  alkalies. 

It  seems,  however,  to  have  been  left  for  Stewart,  Peter- 
son, and  Greaves  (17,  16,  19,  18)  to  explain  clearly  the 
intimate  relation  existing  between  present  alkali  accu- 
mulations and  the  presence  of  large  quantities  of  alkali 
salts  in  country  rocks  from  which  these  soils  were  formed. 
They  made  extensive  examinations  of  the  geological 
formations  in  Utah,  Colorado,  Arizona,  Wyoming,  Idaho, 
and  Nevada,  and  analyzed  the  soil-forming  country  rock 
of  these  areas. 

These  examinations  and  analyses  revealed  the  fact  that 
in  these  sections  wherever  alkali  is  present  in  very  large 


JURASSIC   BEDS  23 

quantities  it  apparently  originated  from  materials  de- 
posited from  concentrated  solutions  in  some  ancient  sea. 
The  deposits  in  the  areas  studied  were  made  during  Cre- 
taceous and  Tertiary  times  which  seemed  to  have  been 
influenced  by  arid  climatic  conditions.  This  area  in- 
cluding the  pastern  part  of  Utah,  the  western  half  of 
Colorado,  and  the  southwestern  part  of  Wyoming  was 
covered  with  water  during  upper  Cretaceous  times  leaving 
the  Uintah  anticline  as  an  island. 

A  description  of  the  method  of  formation  of  these  shales 
and  sandstones  that  are  so  high  in  soluble  salts  is  given 
as  follows  (17): 

"  Jurassic  Beds.  -The  Jurassic  beds  contain  highly 
colored  red,  yellow,  gray,  green,  or  blue  shale  and  sand- 
stone ranging  from  fine  grain  to  coarse  grits.  In  the 
upper  members  of  the  deposit  are  often  found  thin  lenses 
of  limestone  and  an  accumulation  of  gypsum.  The  ac- 
cumulation and  position  of  the  gypsum  beds  would  seem 
to  indicate  that  they  had  resulted  from  precipitation  from 
the  water  of  isolated  brackish  lakes. 

"At  the  end  of  Jurassic  times  the  inland  sea,  in  which 
the  Jurassic  deposit  accumulated,  disappeared  and  the 
area  was  subjected  to  erosion.  This  probably  took  place 
during  lower  Cretaceous  times.  Later  the  section  was 
again  covered  with  an  inland  sea  and  deposits  were  laid 
down  unconformably  on  top  of  the  Jurassic. 

"These  belong  to  the  Dakota  beds,  the  lower  part  of 
which  were  composed  of  conglomerates  and  coarse  sand- 
stones, above  which  are  carbonaceous  shales  and  some  low- 
grade  coal,  overlain  by  more  sandstone  and  highly  colored 
shales.  Above  the  shale  are  found  thick  beds  of  light- 
colored  sandstone,  shales,  and  dark-brown  sandstones. 

"At  about  the  end  of  the  Dakota  period  there  seems  to 


24 


THE  ORIGIN  OF  ALKALI 


have  been  some  shifting  and  readjusting  of  the  land  as  the 
Dakota  beds  are  found  to  be  quite  thick  in  the  northern 
section  where  the  Mancos  are  thin;  while  in  the  southern 
section  the  Mancos  are  found  to  be  exceedingly  thick  in 
places  where  the  Dakota  is  comparatively  thin. 

"  Where  they  are  not  capped  with  the  sandstone  the 
beds  do  not  form  abrupt  ledges,  but  weather  off  into  rather 
rounded  symmetrical  clay  hills —  at  least  they  appear 


FIG.  i.  —  SALT-BEARING  SHALE  FORMATION.    THIS  TYPE  OF  SOIL-    ' 
FORMING  MATERIAL  is  A  COMMON  SOURCE  OF  ALKALI. 

to  be  clay  hills.  This  disintegration  of  the  shales  gives 
rise  to  a  very  sticky,  plastic  clay  which  forms  numerous 
cracks  when  dry,  but  becomes  a  continuous  coat  of  plastic 
clay  when  wet.  The  material  is  so  close  grained  that 
when  rain  falls  upon  it,  it  seals  up  all  the  pores  and  cracks 
so  that  water  does  not  seem  to  penetrate  it.  These  hills 
are  very  sparsely  covered  with  vegetation  and  it  is  not  an 
unusual  thing  to  see  an  area  of  more  than  an  acre  which 
does  not  contain  a  single  plant. 

"On  these  rounded  clay  hills  one  seldom  has  to  dig  more 
than  a  foot  before  the  shale  is  found  in  place.  However, 
the  material  covered  is  not  uniform,  especially  on  top  of  the 
clay  knolls.  The  usual  condition  is  that  on  the  surface 
is  from  one  to  two  inches  of  earthy  clay,  under  which  is 


MONTANA  25 

from  one  to  six  inches  of  what  appears  to  be  a  gray  ashy 
material.  On  close  examination  this  proves  to  be  crystals 
of  salt  together  with  flocculent  clay.  Immediately  under 
this  is  found  the  shale  in  place.  Samples  of  the  clay  and 
gray  ashy  material,  and  the  shale  in  place  were  taken 
separately,  and  the  analyses  show  the  nitrate  contents  of 
each. 

"The  dark-colored  shales  show  numerous  crystals  of 
gypsum  in  the  cracks  and  bedding  planes.  Where  the 
shale  is  dry  and  considerably  weathered  the  gypsum 
appears  like  white  flour.  In  the  seams  of  the  shale,  but 
a  foot  or  more  under  the  surface  in  the  same  place,  the 
crystals  are  still  firm  and  solid. 

"At  Emery,  Utah,  the  gypsum  crystals  were  not  only 
taken  out  of  the  bedding  plane  of  the  thick  layers,  but 
numerous  cross  fractures  were  found  which  were  also 
filled  with  gypsum  crystals.  Many  of  these  cross  fractures 
were  as  much  as  a  half  inch  thick  and  pieces  of  gypsum 
this  thickness  and  a  foot  long  were  removed  from  the 
shales. 

"  Montana. —  Overlying  the  Mancos  is  the  Montana 
Mesa  Verde  formations  which  are  essentially  sandstones, 
shales,  and  grits,  light  gray  to  dark  brown  in  color.  Car- 
bonaceous shales  with  thick  beds  of  workable  coal  occur 
near  their  base,  while  sandstone  occurs  in  the  upper  part. 
1  Transition  marked  by  increase  of  sandstone  upward  and 
appearance  of  brackish  and  fresh  water  arise  instead  of 
marine  conditions.' 

"The  upper  layers  of  sandstone  are  often  found  in  thick 
lenses  and  in  many  places  contain  high  percentages  of 
gypsum.  The  vegetation  accumulated  in  these  shallow 
seas  resulted  in  the  formation  of  coal.  The  sea  seems  to 
have  increased  sufficiently  after  the  formation  of  the  coal 


26  THE  ORIGIN  OF  ALKALI 

so  the  area  was  covered  with  thick  layers  of  sand  and 
shale,  but  the  sea  does  not  seem  to  have  continued  without 
interruption.  Arid  conditions  seem  to  have  again  pre- 
vailed and  the  sea  was  reduced  so  that  isolated  portions 
became  brackish  and  from  these  isolated  waters  gypsum 
and  other  salts  were  precipitated. 

"At  the  end  of  the  Montana  series  the  sea  seems  to 
have  again  entirely  disappeared  and  the  area  was  subject 
to  erosion. 

"In  the  beginning  of  Tertiary  times  the  section  was 


- 

/•  •'  v, 

/>>    ,  •    •     & 


FIG.  2.  —  MANCOS  SHALE  HILL.    SOIL  FROM  THIS  FORMATION 
is  HIGH  IN  ALKALI. 

again  covered  with  inland  seas  over  much  the  same  area 
as  that  occupied  by  the  upper  Cretaceous.  The  lower 
portion  of  these  Tertiary  deposits  consisted  of  yellow  and 
reddish-yellow  sandy  clays  with  regularly  bedded  sand- 
stones, with  some  conglomerates  near  the  base,  over  which 
were  deposited  thin  beds  of  light-colored  sandstones  asso- 
ciated over  much  of  the  area,  especially  in  Utah,  with 
rhyolitic  ash  beds  and  fresh-water  deposits.  In  some 
places  the  ashes  show  distinct  stratification  as  though  they 


ARMS  OF  THE  OCEAN  27 

had  fallen  into  the  inland  sea  and  had  been  worked  over 
by  the  water. 

"The  upper  part  of  the  Tertiary  is  composed  of  shaly 
sandstone  and  arenaceous  shale,  and  in  some  sections 
thick  beds  of  subbituminous  coals.  The  shale  and  much 
of  the  sandstone  are  gypsiferous  and  in  many  places  con- 
tain high  percentages  of  sodium  salts. 

"Near  the  close  of  the  period  the  high  evaporation 
seems  to  have  so  reduced  the  sea  that  parts  of  it  became 
isolated  lakes  and  from  these  brackish  deposits  were 
precipitated  the  salts  and  gypsum  in  question. 

"The  Green  River  formation  is  composed  essentially 
of  light-colored  thinly  laminated  beds,  characterized  by 
light-colored  thin  bedded  shales.  In  appearance  these 
shales  of  the  Green  River  formation  are  much  like  those 
of  the  Mancos,  especially  some  of  the  light-colored  and 
thinner  beds. 

"The  Green  River  shales  weather  into  a  series  of  'bad 
lands,  and  it  is  not  an  unusual  thing  to  have  a  large  area 
entirely  devoid  of  plants." 

Arms  of  the  Ocean.  —  Many  soils  have  been  formed  by 
deltas  of  streams  deposited  in  the  ocean.  These  sometimes 
enclose  portions  of  the  ocean  which  may  be  shut  off  from 
the  main  body  of  water.  The  inclosed  salt  water  gradually 
evaporates  and  leaves  deposits  of  soluble  salts  or  an  alkali 
condition  in  the  soil.  This  may  be  either  a  surface  ac- 
cumulation that  is  comparatively  easy  to  remove,  or  the 
salts  may  extend  to  considerable  depth  and  be  very  difficult 
to  handle.  The  type  depends  on  the  way  in  which  the 
soil  was  laid  down  and  the  nature  of  the  area  of  inclosed 
sea  water.  Subsequent  deposits  of  soil  may  leave  the 
alkali  at  considerable  depths.  The  alkali  land  of  the 
lower  Nile  Valley  as  well  as  the  small  alkali  tract  along 


28  THE  ORIGIN  OF  ALKALI 

the  coast  of  Southern  California  derived  their  soluble 
salts  from  ocean  water,  which  was  inclosed  in  arms  shut 
off  from  the  main  body  of  the  ocean. 

Evaporation  of  Saline  Lakes. —  In  arid  countries  nu- 
merous lakes  without  an  outlet  to  the  sea  are  found.  All 
the  water  running  into  them  is  evaporated  leaving  the 
dissolved  material  to  be  gradually  concentrated  until  the 
waters  become  saturated.  Around  the  bodies  of  these 
lakes  the  soil  is  likely  to  be  high  in  soluble  salts.  Arms  of 
the  lake  may  be  shut  off  in  the  manner  already  described. 
These  become  centers  of  local  salt  accumulation.  The 
lands  for  some  distance  surrounding  these  saline  lakes  are 
likely  to  be  somewhat  impregnated  with  alkali,  but  as  the 
water  is  approached  the  concentration  is  generally  in- 
creased. There  is  usually  a  fringe  near  the  lake  that  is 
entirely  unproductive.  This  is  surrounded  by  a  zone  in 
which  only  alkali-resistant  plants  grow,  and  still  farther 
away  the  less-resistant  plants  are  found.  The  Great  Salt 
Lake  in  Utah  is  an  example  of  this  kind. 

Formation  of  Soluble  Carbonates.  —  On  account  of  their 
soluble  action  on  the  organic  matter  of  the  soil  and  the 
hard  crust  which  they  form  on  the  soil,  the  soluble  car- 
bonates are,  of  all  the  soluble  salts,  most  to  be  dreaded. 
Fortunately,  they  are  not  so  widespread  in  their  occurrence 
as  are  the  chlorides  and  sulphates.  The  comparatively 
insoluble  carbonates  of  calcium  and  magnesium  are  very 
abundant  but,  being  only  slightly  soluble,  they  are  seldom 
if  ever  harmful  to  plants. 

The  exact  method  of  soluble-carbonate  formation  is  not 
well  known.  Cameron  (3),  from  studies  of  greasewood 
and  the  creosote  bush,  held  that  these  plants  are  instru- 
mental in  converting  the  neutral  salts  into  carbonates. 
Aladjem  (i),  from  laboratory  experiments  with  soil  kept 


FORMATION  OF  SOLUBLE   CARBONATES        29 

in  a  water-logged  condition  and  to  which  nitrates  were 
added,  concluded  that  sodium  carbonate  is  readily  formed 
from  the  nitrates  in  a  water-logged  soil. 

Treitz  (22)  concluded  from  his  studies  of  alkali  soils 
of  Hungary  that  the  soluble  salts  found  in  thgm  are  derived 
from  the  ash  constituents  of  the  plants  produced  on  the 
soil  and  that  the  first  and  most  necessary  condition  for 
the  formation  of  sodium  compounds,  particularly  the 
carbonates,  is  a  calcareous  subsoil,  carbonates  of  the 
alkali  being  formed  by  the  action  of  calcium  carbonate  on 
the  humates,  sulphates,  and  chlorides  of  the  alkalies. 

From  a  study  of  water  extracts  of  typical  alkali  soils 
and  of  soils  to  which  various  salts  were  added,  Cedroits  (5) 
concluded  that  sodium  carbonate  is  not  formed  in  the  soil 
by  direct  reaction  between  sodium  chloride  and  calcium 
carbonate,  but  that  the  sodium  of  the  chloride  replaces 
other  bases  —  potassium,  calcium,  and  magnesium  —  in 
humates  and  -silicates,  and  the  latter  give  up  soda  to  the 
soil  solution  when  the  excess  of  soluble  sodium  salts  is 
removed. 

Kelley  (13)  and  Breazeale  (2)  have  concluded  that 
sodium  nitrate  reacts  with  calcium  carbonate  in  the  for- 
mation of  small  quantities  of  sodium  carbonate.  In  dis- 
cussing this  reaction  Breazeale  has  the  following  to  say: 
"In  the  reaction  between  sodium  nitrate  (or  sodium 
chloride  or  sodium  sulphate)  and  calcium  carbonate, 
resulting  in  the  formation  of  sodium  carbonate,  the  presence 
of  relatively  small  amounts  of  calcium  nitrate  or  calcium 
chloride  in  the  reaction  impedes  and  may  prevent  the 
formation  of  sodium  carbonate.  The  presence  of  a  satu- 
rated solution  of  calcium  sulphate  in  this  reaction  does 
not  entirely  stop  the  formation  of  sodium  carbonate. 
Sodium  nitrate,  sodium  chloride,  and  sodium  sulphate  in 


30  THE  ORIGIN  OF  ALKALI 

the  presence  of  carbon  dioxide  react  with  calcium  carbonate, 
with  the  formation  of  sodium  bicarbonate.  The  presence 
of  relatively  small  amounts  of  calcium  nitrate  or  calcium 
chloride  in  this  reaction  impedes  and  finally  prevents  the 
formation  of  sodium  bicarbonate.  The  presence  of  cal- 
cium sulphate  has  no  effect  in  preventing  the  formation 
of  sodium  bicarbonate  when  sodium  sulphate,  or  a  mixture 
containing  sodium  sulphate,  reacts  with  calcium  carbonate. 
Sodium  nitrate,  sodium  chloride,  and  sodium  sulphate 
react  with  calcium  carbonate  in  the  soil  with  the  formation 
of  sodium  carbonate  (black  alkali)." 

Nitrate  Formation.  —  In  alkali  areas  in  many  parts  of 
several  western  states,  certain  brown-colored  spots  are 
found  to  contain  large  quantities  of  nitrates.  Headden 
(10,  n)  and  Sackett  and  Isham  (15)  believe  that  these 
nitrates  are  formed  within  the  soil  by  the  action  of  non- 
symbiotic  nitrogen-fixing  bacteria.  Stewart  and  Greaves 
and  Stewart  and  Peterson  (17,  16,  '18)  are  convinced, 
however,  that  large  quantities  of  nitrates  seep  into  the 
soil  with  the  other  salts  from  the  country  rock  and  that 
local  nitrogen  fixation  is  a  minor  matter  in  the  accumulation 
of  sodium  nitrate  in  alkali  soils. 

Localization  mentioned  by  Headden  is  claimed  by  him 
to  preclude  the  theory  of  transportation  and  concentration 
in  some  cases.  He  states  that  certain  of  the  spots  are  in 
the  center  of  the  valley  the  soil  of  which  is  so  deep  as  to 
preclude  the  theory  of  transportation.  He  also  says  the 
ground  water  about  and  beneath  the  spots  is  not  high  in 
nitrates,  which  again  apparently  contradicts  Stewart  and 
Peterson's  theory. 

Concentration  by  Irrigation  Water.  —  Whatever  the 
original  source  of  alkali  in  the  soil,  one  fact  has  been  well 
demonstrated.  The  condition  may  be  greatly  aggravated 


CONCENTRATION  BY  IRRIGATION  WATER     31 

by  the  improper  use  of  irrigation  water.  The  author  (8) 
and  many  other  workers  have  shown  that  the  soluble  salts 
are  carried  through  the  soil  very  readily  by  irrigation 
water.  In  some  soils,  like  those  in  parts  of  the  large  in- 
terior valleys  of  California,  the  original^  salt  content, 
though  high,  was  not  sufficiently  high  to  prohibit  the 
growth  of  crops.  After  irrigation  the  salts  are  leached 
from  the  higher  land  and  carried  to  the  lower,  here  to  be 
concentrated  at  the  surface  until  the  amount  becomes  too 
great  for  ordinary  crops  to  grow  successfully.  This  con- 
dition is  found  to  an  extent  in  practically  every  large 
irrigated  section  of  the  world.  Methods  of  preventing 
accumulation  in  this  way  will  be  more  fully  discussed  in 
a  later  chapter. 

Considerable  salt  may  also  be  added  directly  to  the 
land  by  the  use  of  irrigation  water  carrying  large  quantities 
of  soluble  salts.  This  method  of  contamination  is  dis- 
cussed rather  fuHy  in  Chapter  XV. 

Relation  of  Origin  to  Methods  of  Treatment.  —  An 
understanding  of  the  origin  of  the  alkali  in  a  given  area 
is  essential  to  an  intelligent  treatment  of  the  condition. 
This  is  as  true  in  handling  a  soil  as  in  treating  a  human 
disease.  A  physician  who  would  give  a  remedy  for  a 
headache  without  seeking  the  cause  of  the  trouble  might 
entirely  fail  in  curing.  He  might  in  any  case  give  some 
simple  treatment  that  would  be  harmless,  but  a  really 
intelligent  treatment  would  be  founded  on  a  knowledge 
of  the  cause  of  the  trouble.  Likewise  in  handling  alkali 
land  the  source  of  the  salt  should  be  known. 

In  one  region  an  irrigation  canal  passed  through  a  shale 
hill  that  was  very  high  in  soluble  salts.  Large  quantities 
were  dissolved  and  taken  directly  into  the  stream.  Seepage 
was  also  excessive  and  much  alkali  was  carried  to  the 


32  THE  ORIGIN  OF  ALKALI 

lower  land  by  the  seepage  water.  The  land  was  finally 
drained,  but  the  alkali  content  of  the  soil  was  not  reduced 
since  the  quantity  added  was  greater  than  that  lost  by 
drainage.  Lining  the  canal  through  the  alkali-charged 
shale  corrected  the  entire  matter.  Soil  experts  and  drain- 
age engineers,  before  deciding  on  the  methods  of  reclaim- 
ing any  alkali  tract,  should  discover  all  probable  sources 
of  the  alkali  in  the  area  under  consideration  and  select 
their  methods  of  reclamation  accordingly. 

REFERENCES 

1.  ALADJEM,  R.     Decomposition  of  Nitrates  as  a  Possible  Cause  of  For- 

mation of  Sodium  Carbonates  in  Egyptian  Soils.     Cairo  Sci.  Jour.  6 
(1912),  No.  75,  pp.  301-302. 

2.  BREAZEALE,  J.  F.     Formation  of   Black  Alkali   (Sodium  Carbonate) 

in  Calcareous  Soils.     Jour.  Agr.  Res.  10  (Sept.  10,  1917),  pp.  541- 
SQO. 

3.  CAMERON,  F.  K.     Formation  of  Sodium  Carbonate,  or  Black  Alkali, 

by  Plants.    U.  S.  D.  A.  Rpt.  No.  71  (1902),  pp.  61-70. 

4.  CAMERON,    F.    K.    The   Soil    Solution,    pp.    110-125.     (Easton,   Pa. 

1911.) 

5.  CEDROITS,  K.  K.     Colloid  Chemistry  in   the  Study  of  Soils.     Russ. 

Jour.  Exp.  Landw.   13   (1912),  pp.  363-420.     (Abs.  E.  S.  R.   28, 
p.  516.) 

6.  CLARKE,  F.  W.    The  Data  of  Geochemistry.    U.  S.  Geol.  Survey, 

Bui.  616  (1916),  pp.  22-35. 

7.  DORSEY,  C.  W.    Alkali  Soils  of  the  United  States.     U.  S.  D.'  A.  Bur. 

of  Soils,  Bui.  35  (1906),  196  pp. 

8.  HARRIS,  F.  S.    The  Movement  of  Soluble  Salts  with  the  Soil  Moisture 

Utah  Sta.  Bui.  139  (1915),  pp.  119-124. 

9.  HEADDEN,  W.  P.    Alkalies  in  Colorado  (including  Nitrates).     Colo. 

Sta.  Bui.  239  (1918),  58  pp. 

10.  HEADDEN,  W.  P.    The  Fixation  of  Nitrogen  in  Some  Colorado  Soils. 

Colo.  Sta.  Bui.  186  (1913),  pp.  3-47. 

11.  HEADDEN,  W.  P.     The  Fixation  of  Nitrogen.     Colo.  Sta.  Buls.  155 

(1910),  48  pp.  and  178  (1911),  pp.  3-96. 

12.  Hilgard,  E.  W.     Soils,  pp.  422-423.     (New  York,  1906.) 

13.  KELLEY,  W.  P.    The  Effects  of  Nitrate  of  Soda  on  Soils.    Cal.  Sta. 

Rpt.  1916,  p.  59. 


REFERENCES  33 

14.  KNIGHT,  W.   C.,  and  SLOSSON,  E.  C.     Alkali  Lakes  and  Deposits. 

Wyo.  Sta.  Bui.  49  (1901),  pp.  75-79- 

15.  SACKETT,  W.  G.,  and  ISHAM,  R.  M.     Origin  of   the  "Niter  Spots" 

in  Certain  Western  Soils.     Science,  n.  ser.  42   (1915),  pp.  452-453. 

1 6.  STEWART,    R.,    and    PETERSON,    W.     Further   Studies   of    the   Nitric 

Nitrogen  Content  of  the  Country  Rock.     Utah  Sta.  Bui.  150  (1917), 
20  pp.  \ 

17.  STEWART,  R.,  and  PETERSON,  W.    The  Nitric  Nitrogen  Content  of  the 

Country  Rock.     Utah  Sta.  Bui.   134  (1914),  pp.  421-465. 
STEWART,  R.,  and  GREAVES,  J.  E.     The  Movement  of  Nitric  Nitro- 
gen in  Soil  and  Its  Relation  to  "Nitrogen  Fixation."     Utah  Sta. 
Bui.  114  (1911),  pp.  181-194. 

18.  STEWART,  R.,  and  PETERSON,  W.    Origin   of  Alkali.    Jour.  Agr.  Res. 

Vol.  10  (Aug.  13,  1917),  pp.  331-353. 

19.  STEWART,  R.,  and  PETERSON,  W.    The  Origin  of  "Niter  Spots"  in 

Certain   Western   Soils.      Jour.  Am.   Soc.  Agron.   Vol.  6   (1915), 
pp.  241-248. 

20.  TRAPHAGEN,  F.  W.    The  Alkali  Soils  of  Montana.    Mont.  Sta.  Bui. 

18  (1898),  pp.  22-23. 

21.  TRAPHAGEN,  F.  W.    The  Alkali  Soils  of  Montana.    Mont.  Sta.  Bui. 

54  (1904),  pp.  91-93. 

22.  TREITZ,  P.    The  Alkali  Soils  of  the  Great  Hungarian  Alfold  Foldtani 

Kozlony,  38  (1908),  pp.  106-131.     (Abs.  E.  S.  R.  20,  p.  818.) 

23.  WHITNEY,  M.,  and  MEANS,  T.  H.    The  Alkali  Soils  of  the  Yellowstone 

Valley.    U.  S.  D.  A.  Bur.  of  Soils,  Bui.  14  (1898),  pp.  9-20. 


CHAPTER  IV 
NATURE  OF  ALKALI  INJURY  TO  THE  PLANT 

MANY  of  the  general  effects  of  excessive  quantities  of 
soluble  salts  in  the  soil  are  well  known,  but  there  still 
remain  to  be  worked  out  a  number  of  important  problems, 
the  solution  of  which  will  throw  a  great  deal  of  light  on  the 
exact  nature  of  alkali  injury.  Every  farmer  in  alkali 
regions  recognizes  by  the  appearance  of  the  soil  and  the 
limitations  in  crop  growth  the  presence  of  alkali,  but  the 
actual  underlying  causes  of  the  abnormal  conditions  are  in 
part  a  mystery  to  even  the  most  profound  students  of  the 
subject. 

Prevention  of  Water  Absorption.  —  Doubtless  one  of 
the  very  important  injuries  caused  by  alkali  results  from 
checked  absorption  of  water  by  plants.  It  matters  not 
how  desirable  other  conditions  are  —  how  much  plant- 
food  is  available,  how  deep  the  soil,  or  how  favorable  the 
temperature  —  if  the  plant  cannot  secure  water  it  can  make 
no  growth.  Roots  absorb  water  from  the  soil  by  the 
process  of  osmosis.  Because  the  cell-sap  of  root-hairs 
contains  a  stronger  solution  than  the  soil,  water  passes 
through  the  cell-wall  and  plasma  membrane  into  the  cell 
where  it  assists  in  the  vital  processes  of  the  plant.  Since 
carbohydrates  are  constantly  being  elaborated  in  the 
leaves,  the  cell-sap  farthest  from  the  roots  is  more  con- 
centrated than  that  which  has  recently  been  diluted  in  the 
roots  by  the  entrance  of  water  from  the  soil.  The  transpi- 

34 


PREVENTION  OF  WATER  ABSORPTION         35 


FIG.  3.  — UPPER,  NORMAL  PLANT  CELL.    LOWER,  CELL 
THAT  HAS  BEEN  PlASMOLYZED. 

ration  of  water  from  the  leaves  also  tends  to  concentrate 
the  cell-sap  in  the  leaves.  This  continuous  diluting  in 
the  roots  and  concentration  in  the  leaves  causes  a  move- 
ment of  water  from  root  cells  upward  toward  the  leaf 


36    NATURE  OF  ALKALI  INJURY  TO  THE  PLANT 

cells.  This  movement  is  necessary  to  the  normal,  function- 
ing of  plants.  An  ordinary  plant,  such  as  wheat,  absorbs 
and  transpires  several  times  its  own  weight  of  water  each 
day.  Should  this  movement  be  reduced,  the  growth  of 
the  plant  is  retarded.  If  it  is  entirely  shut  off  the  plant 
dies,  as  pointed  out  by  Pfeffer  (12). 

The  exact  action  that  takes  place  when  a  plant  cell  comes 
in  contact  with  a  solution  more  concentrated  than  its  own 
content  was  long  ago  pointed  out  by  deVries  (15)  and 
Pfeffer  (n).  Water  passes  out  of  the  cell  and  the  plasma 
membrane  draws  away  from  the  cell-wall  leaving  the  cell 
in  a  plasmolyzed  condition.  The  rapidity  of  plasmolysis 
depends  on  the  relative  concentration  of  the  solution 
inside  and  outside  of  the  cell.  So  well  known  is  this 
phenomenon  that  the  method  is  used  constantly  in  de- 
termining the  concentration  of  the  cell-sap  under  various 
conditions. 

The  above  conception  helps  to  explain  the  observed 
action  of  plants.  The  soil  solution  of  land  high  in  alkali  is 
stronger  than  the  cell-sap;  therefore,  no  plant  growth 
takes  place.  In  other  land  where  there  is  less  alkali,  the 
concentration  may  be  just  strong  enough  to  reduce  the 
rate  of  water  absorption  but  not  enough  to  shut  it  off 
entirely.  Under  this  condition  the  crop  yield  would  be 
reduced.  Thus,  every  gradation  from  a  normal  crop  to 
no  crop  at  all  may  be  found  in  a  single  field. 

Under  some  conditions,  such  as  after  irrigation  or  heavy 
rains,  alkali  may  be  so  diffused  throughout  the  soil  that  the 
concentration  at  any  point  is  not  sufficient  to  prevent  the 
crop  from  beginning  a  good  growth.  As  the  season  ad- 
vances, the  salt  may  accumulate  at  the  surface  of  the 
soil  until  irrigation  water  is  applied.  It  may  then  be 
washed  down  to  the  roots  in  a  concentrated  form  causing 


EFFECTS  ON   GERMINATION  37 

the  death  of  the  plant.  The  farmer  says  his  crop  has  been 
burned  since  it  has  that  appearance.  As  a  matter  of  fact 
water  may  have  been  drawn  out  of  the  plant  through  the 
roots.  This,  taken  with  the  loss  by  transpiration,  des- 
sicates  the  piant  to  the  point  at  which  it  dies. 

Effects  on  Germination.  —  Before  a  seed  can  germinate 
it  must  absorb  water.  Ordinarily  when  a  seed  is  planted 
in  a  moist  soil  it  absorbs  moisture  and  swells.  At  once 


FIG.  4.  —  AN  ORCHARD  PLANTED  ON  LAND  THAT  CAME  FROM  A  FORMATION 
HIGH  IN  SOLUBLE  SALTS.  THE  SALTS  HAD  KILLED  MOST  OF  THE  TREES 
BY  THE  SECOND  YEAR. 

the  enzymes  contained  in  the  seed  convert  part  of  the 
starch  into  sugar  which  increases  the  strength  of  the  solu- 
tion in  the  seed.  This  in  turn  hastens  absorption  and  the 
seed  soon  contains  sufficient  moisture  with  which  to  carry 
on  rapid  cell  division  and  growth.  Within  a  few  days  a 
root  is  sent  out,  then  a  shoot  for  the  top,  and  a  new  plant 
is  growing. 

When  a  seed  is  placed  in  a  strong  salt  solution  or  a  soil 
that  has  a  large  amount  of  alkali,  it  does  not  absorb  mois- 
ture; consequently,  it  lies  dormant  the  same  as  it  would  in 
dry  soil  or  in  dry  air.  The  coating  on  the  seed  protects  it 
from  absorbing  most  of  the  salts.  It  may  not  be  injured, 
and  as  pointed  out  by  Slosson  (13)  it  will  germinate  when 
removed  from  the  alkali  soil  to  conditions  favoring  ger- 


38    NATURE  OF  ALKALI  INJURY  TO  THE  PLANT 

mination.  Under  similar  conditions,  a  plant  would  not 
only  be  hindered  from  growing,  but  would  actually  be 
killed. 

A  salt  solution  not  sufficiently  strong  to  prevent  entirely 
the  germination  of  seeds  may  greatly  delay  it.  The  author 
has  shown  (3)  that  seeds  which  normally  germinate  in  six 
days  may  be  delayed  as  long  as  twenty-one  days  under 
conditions  in  eyery  way  similar  except  in  the  salt  content  of 
the  soil.  This  delayed  germination  may  be  very  serious 
in  regions  where  the  normal  length  of  the  growing  season 
is  greater  than  that  required  for  maturity  of  the  crop  even 
if  growth  after  germination  were  satisfactory. 

Effect  on  Structure  of  the  Plant.  —  Vegetation  growing 
on  alkali  soil  has  a  characteristic  appearance  similar  to 
that  found  growing  under  desert  conditions.  It  generally 
lacks  that  bright  green  appearance  of  vigorous  and  healthy 
growth.  This  condition  is  observed  even  in  water-logged 
land  where  there  is  an  ample  supply  of  moisture.  A 
similar  moisture  supply  without  alkali  would  result  in  a 
succulent  growth. 

Harter  (4)  examined  the  structure  of  plants  to  determine 
the  effect  of  soluble  salts  in  the  soil.  He  found  that  culture 
in  a  soil  containing  considerable  quantities  of  sodium 
chloride  together  with  other  salts  produced  measurable 
changes  in  the  leaf  structure  of  wheat,  oats,  and  barley. 
The  most  notable  modification  produced  was  the  conspicu- 
ous bloom  or  waxy  deposit  that  formed  on  the  surface  of 
the  leaves.  This  development  of  bloom  was  accompanied 
by  an  easily  measured  increase  in  the  thickness  of  the  cuticle 
and  outer  walls  of  the  epidermal  cells  and  by  a  marked 
decrease  in  their  size. 

In  regard  to  transpiration  of  the  plants,  it  was  found 
that  when  the  alkali  salts  are  present  in  sufficient  con- 


INJURY  AT  THE  SURFACE  OF  THE  SOIL      39 

centration  to  cause  the  modifications  of  structure  noted, 
transpiration  is  much  reduced.  On  the  other  hand,  the 
same  salts  when  present  in  amounts  too  small  to  produce 
any  measurable  influence  upon  structure  have  a  decidedly 
stimulating  effect  upon  transpiration. 


FIG.  5.  —  THE  LOWER  PART  OF  AN  ORCHARD  BEING  KILLED  BY 
ALKALI  BROUGHT  TO  THE  SURFACE  BY  A  RISING  WATER  TABLE. 

Similar  modifications  in  structure  have  been  pointed 
out  by  Kearney  (7)  who  shows  that  thickness  of  leaves  and 
stems  with  zerophytic  tendencies  characterizes  plants 
growing  in  a  saline  soil 

Injury  at  the  Surface  of  the  Soil.  —  Orchards  and  vine- 
yards in  many  cases  have  been  planted  in  soils  containing 
a  rather  high  salt  content,  but  not  high  enough  to  prevent 
growth.  A  root  system  may  become  thoroughly  estab- 
lished in  an  untoxic  lower  layer  of  soil  which  is  slightly 


40    NATURE  OF  ALKALI  INJURY  TO  THE  PLANT 

alkaline  and  yet  there  may  be  a  gradual  accumulation  of 
salt  at  the  surface  of  the  soil.  This  condition  has  the 
effect  of  corroding  the  plant  and  it  often  destroys  the  bark 
so  thoroughly  that  the  passage  of  elaborated  food  from 
leaves  to  roots  is  prevented.  This  injury  is  rather  limited 
in  the  total  damage  done  and  may  be  overcome  without 
great  expense. 

Formerly  it  was  thought  that  the  principal  injury  to 
vegetation  by  alkali  resulted  from  a  corroding  action. 
This  is  probably  not  the  case,  with  the  possible  exception 
of  the  carbonates.  The  carbonates,  in  addition  to  any 
direct  action  on  the  plant  itself,  make  the  soil  hard  and  a 
poor  medium  for  the  plant. 


REFERENCES 

1.  BREAZEALE,  J.  F.    Effect  of  Sodium  Salts  in  Water  Cultures  on  the 

Absorption  of  Plant-food  by  Wheat  Seedlings.  Jour.  Agr.  Res.  7 
(1916),  pp.  407-416. 

2.  DUGGAR,  B.  M.     Plant  Physiology,  pp.  64-83.     (New  York,  1911.) 

3.  HARRIS,  F.  S.    Effect  of  Alkali  Salts  in  Soils  on  the  Germination  and 

Growth  of  Crops.     Jour.  Agr.  Res.  5  (1915),  pp.  1-52. 

4.  HARTER,  L.  L.     Influence  of  a  Mixture  of  Soluble  Salts,  principally 

Sodium  Chloride,  upon  the  Leaf  Structure  and  Transpiration  of 
Wheat,  Oats,  and  Barley.  U.  S.  D.  A.  Bur.  PL  Ind.  Bui.  134  (1908), 
19  pp. 

5.  HICKS,  G.  H.    The  Germination  of  Seeds  as  Affected  by  Certain  Chemi- 

cal Fertilizers.     U.  S.  D.  A.  Div.  Botany,  Bui.  24  (1900),  15  pp. 

6.  HILGARD,  E.  W.     Soils,  pp.  326-428.     (New  York,  1906.) 

7.  KEARNEY,  T.  H.,  and  CAMERON,  F.  K.     Some  Mutual  Relations  be- 

tween Alkali,  Soils,  and  Vegetation.  U.  S.  D.  A.  Rpt.  71  (1902), 
60  pp. 

8.  JOST,  L.    Plant  Physiology,  pp.   11-35.     (Oxford,   1907.) 

9.  KEARNEY,  T.  H.    Plant  Life  in  Saline  Soils.    Jour.  Wash.  Acad.  of 

Sci.  Vol.  8  (1918). 

10.  MICHEELS,  H.  The  Mode  of  Action  of  Weak  Solutions  of  Electro- 
lytes on  Germination.  Acad.  Roy.  Belg.  Cl.  Soc.  (1912),  No.  n, 
PP.  753-765.  (Abs.  E.  S.  R.  29,  p.  218.) 


REFERENCES  41 

11.  PFEFFER,  W.     Osmotische  Untersuchungen  (1877),  236  pp. 

12.  PFEFFER,  \V.     Physiology  of  Plants,  Vol.  i  (1900),  pp.  90-107;  Vol.  2 

(1903),  pp.  249-258. 

13.  SLOSSON,  E.  E.     Alkali  Studies.    Wyo.  Sta.  Rpt.  1899,  29  PP- 

14.  TRUE,    R.   H.    The   Physiological   Action   of   Certain   Plasmolyzing 

Agents.     Bot.  Gaz.  Vol.   26   (1898),  pp.  407-416. 

15.  VRIES,  H.  DE.     Eine  Methode  zur  Analyse  der  Turgorkraft.     Jahr. 

f.  wiss,  Bot.  14  (1884),  pp.  427-601. 


CHAPTER  V 
TOXIC   LIMITS   OF  ALKALI 

NUMEROUS  attempts  have  been  made  to  determine  the 
approximate  quantity  of  the  different  alkali  salts,  both 
singly  and  in  various  combinations,  which  may  be  with- 
stood successfully  by  crops.  Some  experimenters  have 
confined  their  work  almost  entirely  to  field  observations. 
Others  have  worked  with  natural  alkali  soils  from  the 
fields  or  soils  made  alkaline  by  the  addition  of  salts  in 
definite  quantities  and  sown  to  crops  under  laboratory 
conditions.  Still  others  have  used  different  solutions 
containing  salts  as  the  medium  for  determining  the  toxicity 
of  salts  to  plants.  Each  method  has  both  advantages  and 
disadvantages. 

The  field  work  has  often  been  done  by  sampling  soils 
showing  injury  to  plants  and  also  adjoining  soils  where 
the  effects  of  the  alkali  could  not  be  detected.  These 
observations  are  usually  taken  after  the  crop  has  made 
considerable  growth,  when  the  extent  of  injury  may  be 
estimated  by  the  appearance  of  the  plants.  Such  deter- 
minations may  not  take  into  consideration  conditions  pre- 
vailing during  the  earlier  stages  of  growth.  The  vigor  and 
delicacy  of  the  plant  at  the  time  the  alkali  comes  in  contact 
with  it  appear  to  have  much  to  do  with  its  tolerance. 
Alfalfa,  sugar-beets,  and  a  number  of  other  plants  do  not 
withstand  alkali  well  in  their  seedling  stages,  but  are 
among  the  most  tolerant  during  later  stages  of  growth. 
Most  plants  do  better  under  alkali  conditions  as  maturity 

42 


NUTRIENT    SOLUTIONS  43 

approaches.  Since  the  conditions  under  which  plants 
grow  at  different  times  is  modified  by  rainfall,  movement 
of  ground^  water,  evaporation,  and  other  factors,  an  analysis 
of  the  soils  at  a  particular  period  of  growth  is  not  so  definite 
for  indicating  toxicity  as  might  be  wished*.  Because  of 
the  difficulty  in  fixing  definite  toxic  limits  under  field 
conditions,  these  observations  will  not  be  considered  in 
the  present  discussion  but  will  be  reserved  for  Chapter  XIV 
dealing  with  crops  for  alkali  land. 

Toxicity  in  Solution.  —  Some  of  the  first  attempts  to 
establish  the  toxic  limits  of  alkali  were  made  in  solution 
cultures  because  the  solution  was  easy  to  make  up,  easy 
to  analyze  subsequently  where  it  was  desired  to  learn  the 
final  concentration  of  the  water,  and  because  such  com- 
plicating factors  as  absorption  of  the  salts,  moisture  con- 
tent of  the  soil,  and  nature  of  the  soil  were  eliminated. 
Some  of  the  experiments  were  carried  on  in  cultural  media, 
such  as  Knop's  solution,  in  an  attempt  to  duplicate  soil 
conditions  as  nearly  as  possible,  whereas  others  were  made 
in  water  containing  only  alkali  salts. 

Nutrient  Solutions. —  Some  of  the  nutrient-solution 
cultures  were  carried  to  later  stages  of  growth  than  those 
with  the  toxic  salts  alone.  Since,  however,  the  strength 
of  the  nutrient  solution,  its  composition,  and  other  factors 
modify  the  results  almost  as  much  in  some  cases  as  the 
alkali  salts  the  advantages  of  the  culture  media  over  the 
simple  solutions  are  not  so  apparent.  Plants  are  usually 
at  their  most  critical  life  period  in  the  seedling  stages 
where  they  are  still  depending  on  the  seed  for  their  nu- 
trition. The  results  of  LeClerc  and  Breazeale  (17)  show 
the  tolerance  of  wheat  seedlings  for  sodium  chloride  in 
culture  solutions  to  be  about  3000  parts  per  million, 
which  is  not  essentially  different  from  certain  other  results 


44  TOXIC  LIMITS  OF  ALKALI 

where  the  solution  containing  the  alkali  salts  was  tap 
water.  Tottingham  (29)  did  not  find  the  introduction  of 
potassium  chloride  or  sodium  chloride  into  Knop's  solution 
to  have  any  marked  effect  on  wheat  plants,  although  the 
sodium  chloride  depressed  the  dry  weight  and  length  of 
roots  of  buckwheat. 

Alkali  Solutions.  —  Alkali  solutions  have  been  used  in 
a  number  of  different  ways  to  determine  toxicity.  Some 
experimenters  have  germinated  the  seed  in  the  alkali  solu- 
tions; others  have  used  the  alkali  solutions  in  which  to 
immerse  the  roots  of  the  seedlings  after  they  have  germi- 
nated under  normal  conditions.  Since  conditions  differ 
so  widely  under  the  two  methods  and  because  the  time 
allowed  for  the  alkali  to  become  effective  differs  consider- 
ably, the  two  methods  will  be  treated  separately. 

Seed  Germination.  —  Experiments  with  wheat  in 
Wyoming  (4,  27)  show  that  salts  hinder  the  absorption 
of  water  by  the  seed  so  that  germination  is  retarded  and 
that  the  kind  of  neutral  salt  is  of  less  importance  than  the 
osmotic  pressure  of  the  solution.  The  work  of  Kearney 
and  Cameron  (14)  on  antagonism  and  of  the  author  (10) 
apparently  disprove  the  latter  statement,  however.  From 
the  Wyoming  experiments  which  included  salt  solutions 
from  loco  to  90,000  parts  per  million  in  strength,  it  was 
found  that  inhibition  was  not  retarded  in  as  rapid  pro- 
portion as  the  osmotic  pressure  of  the  solution  was  in- 
creased. Inhibition  was  apparently  not  influenced  by  the 
vitality  of  the  seed  nor  did  the  salts  affect  the  vitality  of 
the  seed  when  removed  before  sprouting.  The  weaker 
solutions  up  to  4000  parts  per  million  of  sodium  sulphate, 
sodium  chloride,  magnesium  sulphate,  or  sodium  car- 
bonate had  a  beneficial  effect  on  the  germination  of  the 
seed  and  the  growth  of  the  plants. 


SEED    GERMINATION  45 

Miss  M  ago  wan  (19)  states  that  alkali  experiments  are 
not  reliable  when  they  are  continued  only  a  week  because 
the  relative  toxicity  of  the  salts  may  change  later.  She 
found  that  although  magnesium  chloride  was  at  first  the 
most  toxic  of  the  chlorides,  followed  by  socUum  chloride, 
potassium  chloride,  and  calcium  chloride,  this  relation- 
ship did  not  hold  throughout  the  experiment. 

Working  with  wheat  seedlings  in  solutions  of  o.oi  normal, 
or  585  parts  per  million,  sodium  chloride,  850  parts  per 
million  sodium  nitrate,  746  parts  per  million  potassium 
chloride,  and  ion  parts  per  million  potassium  nitrate, 
Micheels  (21)  found  chlorine  more  harmful  than  nitrate 
ions,  and  sodium  more  harmful  than  potassium  ions.  He 
ascribed  the  variation  to  physiological  and  not  chemical 
differences,  as  did  also  Slosson  and  Buffum  (27)  working 
with  wheat,  rye,  and  beans  in  the  common  alkali  salt 
solutions.  Sodium  carbonate  was  the  only  salt  found 
causing  other  than  physiological  injury. 

Wyoming  experiments  (27)  show  the  highest  concentra- 
tion of  salts  not  retarding  germination  of  wheat  and  rye 
to  be  as  follows: 

MgSO4  Na2S04  NaCl  Na2CO3 

Wheat 10,000  7000  4000  4000 

Rye 10,000  7000  4000  1000 

The  vitality  and  time  to  germinate  were  effected  dele- 
teriously  as  the  strength  increased  above  the  minimum. 
Rye  was  as  a  general  rule  more  tolerant  of  the  higher 
concentrations  of  these  salts  than  was  wheat. 

Sigmund  (26)  found  5000  parts  per  million  of  sodium 
chloride  or  of  sodium  carbonate  retarded  the  germination 
of  cereal  seeds  in  solutions  of  these  salts.  Vetch  and 
rape  seeds  were  killed  in  5000  parts  per  million  solutions 


46  TOXIC  LIMITS  OF  ALKALI 

of  sodium  carbonate,  but  neither  they  nor  wheat  were 
injured  in  5000  parts  per  million  of  sodium  bicarbonate. 
According  to  this  author  the  highest  strength  of  sodium 
chloride  endurable  by  the  cereals  was  5000  parts  per  mil- 
lion, by  legumes  3000  parts  per  million,  and  by  rape  1000 
parts  per  million.  Jarius,  as  quoted  by  Kearney  and 
Cameron  (14),  reports  a  stimulating  effect  on  seeds  of 
wheat,  rye,  rape,  maize,  beans,  and  vetch  in  a  solution 
containing  4000  parts  per  million  of  sodium  chloride. 
Storp,  as  quoted  from  Kearney  and  Cameron  (14),  found 
this  salt  to  stimulate  germination  in  solutions  as  strong  as 
100  parts  per  million.  In  his  work  with  solutions  of  sodium 
chloride  in  concentrations  ranging  from  1250  to  50,000 
parts  per  million,  Coupin  (6)  found  the  toxic  limits  for 
wheat  to  be  18,000  parts  per  million,  of  lupine  22,000  parts 
per  million,  of  maize  14,000  parts  per  million,  of  peas  12,000 
parts  per  million,  and  of  vetch  11,000  parts  per  million. 
In  this  author's  experiment  the  endurance  of  the  plant  as 
a  whole  to  the  solution  was  taken  to  indicate  the  limit, 
whereas  with  some  of  the  others  the  death  of  the  root  or 
some  other  part  is  sometimes  taken  to  indicate  the  injury 
to  the  plant.  He  found  the  toxic  limits  for  seashore  plants 
to  be  several  times  that  for  the  crop  plants  mentioned 
above.  Nessler,  who  is  quoted  by  Hicks  (12),  states  that 
hemp  seed  was  injured  in  germinating  by  2500  parts  per 
million  of  sodium  chloride,  clover  by  5000  parts  per  mil- 
lion, and  wheat  by  10,000  parts  per  million.  Rape  seed 
was  found  to  resist  sodium  chloride,  potassium  chloride, 
calcium  nitrate,  sodium  nitrate,  and  potassium  sulphate 
in  concentrations  as  high  as  5000  parts  per  million,  but 
the  vitality  of  wheat,  rye,  maize,  beans,  and  peas  was 
seriously  injured  when  using  solutions  as  strong  as  this  (12). 
Sodium  chloride  had  a  stimulating  effect. 


SEEDLINGS  IN  ALKALINE  SOLUTIONS         47 

Seedling  Transference  into  Alkaline  Solutions. —  This 
practice  kas  been  preferred  to  germinating  and  growing 
the  plants  in  the  alkaline  solutions  by  some  investigators. 
Certain  experiments  have  indicated  that  plants  may 
gradually  become  accustomed  to  salts  as  they  grow  older 
so  that  the  injurious  strength  of  solution  at  one  period 
may  not  be  so  at  another.  By  dipping  the  seedlings  into 
the  alkali  solutions  at  a  definite  period  after  germinating, 
it  has  been  hoped  that  a  better  standard  for  comparing 
toxicity  would  be  fixed.  For  such  work  many  standard 
conditions  have  been  suggested  but  few  of  these  standards 
have  been  accepted  by  other  workers,  so  there  is  a  wide 
difference  in  the  conditions  under  which  the  toxicity  of 
the  plants  have  been  determined. 

In  the  experiments  of  Kearney  (13)  and  his  co-workers 
the  roots  of  the  seedlings  were  placed  in  the  alkali  solu- 
tions for  twenty-four  hours  and  the  death  of  the  root  tip 
was  taken  to  indicate  the  toxic  limit  for  the  plant.  As 
a  result  of  this  work,  corn  showed  the  toxic  effect  of  mag- 
nesium less  than  other  salts,  but  with  lupines,  alfalfa,  wheat, 
sorghum,  oats,  cotton,  and  beets  the  magnesium  compounds 
were  considerably  more  toxic  than  other  salts.  The  sodium 
chloride  and  sodium  sulphate  did  not  differ  greatly  in 
toxicity  to  the  different  plants  in  several  cases,  and  the 
sodium  carbonate  was  several  times  more  toxic  than  these 
two  salts  in  most  cases.  Corn,  which  is  considered  rather 
sensitive  to  alkali,  endured  more  sodium  carbonate  than 
the  other  crops,  whereas  sorghum,  cotton,  and  beets, 
which  are  usually  resistant  in  soils,  were  affected  most 
by  this  salt  in  solution.  The  limits  for  wheat  were  650 
parts  per  million  of  sodium  carbonate,  2610  parts  per 
million  of  sodium  chloride,  and  2830  parts  per  million  of 
sodium  sulphate.  Comparing  the  two  series  with  lupines 


48  TOXIC  LIMITS  OF  ALKALI 

it  is  seen  that  the  variations  are  wide.  In  another  experi- 
ment with  lupine,  where  growth  was  prevented  by  the 
salts  contained  in  the  solutions,  the  magnesium  salts  were 
not  so  toxic  as  the  carbonates  of  sodium,  and  the  mag- 
nesium sulphate  was  the  least  toxic  of  all  salts.  This 
shows  that  very  wide  differences  might  be  expected  ac- 
cording to  the  method  employed. 

True  (30),  using  the  above  method  for  obtaining  the 
toxic  limit  of  lupine  in  sodium  chloride  solutions  found 
it  to  be  3625  parts  per  million,  which  again  shows  the 
possible  error.  Coupin  (5)  allowed  the  plants  to  remain 
in  the  solutions  until  the  whole  plant  showed  the  salts 
to  be  causing  injury.  His  limits  for  lupine  using  sodium 
chloride,  magnesium  chloride,  and  magnesium  sulphate 
were  12,000,  8000,  and  10,000  parts  per  million  for  the 
respective  solutions,  which  is  about  the  same  as  the 
above  results  where  growth  was  prevented. 

The  resistance  here  is  several  times  that  found  by  Harter 
where  the  first  injury  was  the  point  of  indication  rather 
than  the  death  of  the  plant.  Allowing  the  roots  to  remain 
in  the  salt  solution  twenty-one  days  and  then  weighing, 
the  author  (10)  found  wheat  seedlings  to  produce  about 
one-half  as  much  as  the  check  in  the  solutions  containing 
5000  parts  per  million  of  sodium  carbonate,  or  in  those 
containing  over  10,000  parts  per  million  of  sodium  chloride 
or  sodium  sulphate.  Haselhoff  (9)  concluded  that  growth 
might  be  inhibited  with  a  5ooo-parts-per-million  solution 
of  sodium  chloride  and  injury  would  result  in  the  presence 
of  500  parts  per  million. 

Hansteen  (8)  states  that  5000  parts  per  million  of  salts 
other  than  calcium  are  injurious  when  used  singly,  but 
when  combined  with  lime  the  injury  is  greatly  diminished. 
Others  have  found  the  same  antagonistic  effects  of  dif- 


IN  SAND  49 

ferent  sajts.    This  subject  is  reserved  for  Chapter  VIII 
and  will  not  be  discussed  here. 

A  series  of  experiments  was  made  by  Marchal  (20)  to 
discover  the  effect  of  salts  on  the  bacterial  activities  of 
the  nodules  of  pea  roots.  He  found  alkaline  nitrates  in 
concentrations  of  100  parts  per  million  checked  the  tu- 
'bercle  production  in  water  cultures.  Ammonium  salts 
were  injurious  in  concentrations  of  500  parts  per  million. 
Potassium  salts  at  5000  parts  per  million  and  sodium 
salts  at  3333  parts  per  million  tended  to  retard  symbiosis, 
but  calcium  and  magnesium  salts  favored  it. 

Soil  Results.  —  Soil  studies  of  alkali  have  been  found 
to  show  less  variation  for  like  treatment  than  solution 
studies.  Some  of  the  other  disadvantages  of  solution 
studies  of  the  effect  of  alkali  on  the  higher  plants  are  that 
the  seed  in  germination  tests  and  the  root  system  are  placed 
in  an  unnatural  environment,  the  air  circulation  being 
eliminated  and  the  normal  resistance  of  the  soil  being 
changed.  Studies  of  plants  in  solutions  compared  with 
similar  soil  cultures  have  shown  that  physiological  dis- 
turbances are  more  likely  to  occur  in  solutions  than  in 
soils;  the  root-hairs  are  less  numerous  and  the  roots  grow 
longer  and  thinner  in  the  solution  than  in  the  soil.  In- 
dividuals show  much  more  variation  due  to  unfavorable 
causes  in  the  solutions  than  in  the  soils  even  where  the 
soil  consists  of  sand  containing  practically  no  nourishment. 

In  Sand.  —  -  The  physical  conditions  under  which  the 
plants  grow  seem  to  have  some  influence  on  their  natural 
development.  The  author  (10)  found  that  whereas  wheat 
seedlings  produced  about  a  half  normal  crop  of  dry  matter 
in  a  sand  containing  1000  parts  per  million  of  sodium 
chloride  in  solution  cultures,  more  than  half  a  normal 
crop  was  obtained  when  the  concentration  was  over  10,000 


50 


TOXIC  LIMITS  OF  ALKALI 


parts  per  million  of  this  salt.  For  sodium  carbonate  the 
relationship  between  sand  and  solution  cultures  was  about 
1000  and  5000  parts  per  million,  respectively,  and  for 
sodium  sulphate  it  was  about  5000  to  over  10,000  parts 
per  million,  respectively,  for  half-normal  crops  of  dry 
matter.  Le  Clerc  and  Breazeale  (17)  found  wheat  seed- 
lings more  tolerant  for  sodium  chloride  in  sand  than  in 
solution.  Breazeale  (2)  states  that  the  reverse  relation- 


FIG.  6.  —  EXPERIMENTS  TO  DETERMINE  THE  TOXICITY  OF 
VARIOUS  ALKALI  SALTS. 

ship  for  nutrient  solutions  holds,  300  parts  per  million  of 
nutrient  solution  being  the  best  concentration  for  wheat 
seedlings,  while  2500  parts  per  million  was  best  for  them  in 
sand.  Others  have  found  the  latter  relationship  to  hold 
for  sand.  The  size  of  pure  quartz  sand  particles  ap- 
parently had  no  effect  on  the  toxicity  of  alkali  in  tests 
made  by  Harris  and  Pittman  (n),  but  the  quantity  of 
moisture  in  the  soil  had  considerable  influence. 

The  differences  which  may  be  expected  in  alkali  experi- 
ments with  differing  moisture  contents  are  shown  in  tests 


IN  SAND  51 

made  by  the  author  (10).  The  toxic  limits  of  wheat  for 
salts  in  a  sand  were  as  follows:  sodium  chloride  with  12 
per  cent  moisture  2900  parts  per  millon,  with  18  per  cent 
5700  parts  per  million;  sodium  carbonate  with  12  per  cent 
2700  parts  per  million,  with  21  per  cent  3300  parts  per 
million;  sodium  sulphate  with  12  per  cent  8000  parts  per 
million,  with  24  per  cent  16,000  parts  per  million.  When 
the  salts  were  added  dry  to  the  soil  rather  than  in  solution 
as  in  the  above  experiments,  the  limits  of  tolerance  were 
higher,  but  the  quantity  of  moisture  added  to  the  soils 
would  influence  the  permissible  quantity  even  more  in 
such  experiments  than  where  the  solutions  were  added  be- 
cause the  quantity  dissolved  would  be  more  dependent  on 
the  water  present. 

In  the  work  of  Buffum  and  Slosson  (4)  sand  was  used  as 
the  medium  for  growing  seed  in  a  nutrient  solution,  an 
attempt  being  made  to  duplicate  soil  conditions  as  nearly 
as  possible.  Their  work  was  with  wheat  and  alfalfa  in 
sand  containing  solutions  with  osmotic  pressure  equivalent 
to  2.03,  3.80,  and  7.10  atmospheres  which  corresponds  to 
5000,  10,000,  and  20,000  parts  per  million  of  sodium  sul- 
phate, or  2700,  5100,  and  9700  parts  per  million  of  sodium 
chloride.  The  conclusions  were  that  the  lower  concentra- 
tions of  the  salts  were  stimulating  to  the  plants  bu'c  that 
the  higher  ones  were  harmful.  Solutions  of  sodium  sul- 
phate, potassium  sulphate,  sodium  chloride,  and  potassium 
chloride  were  all  about  equally  harmful  to  those  plants  at 
the  same  osmotic  pressures  when  based  on  germination 
and  several  other  observations  of  the  growing  plants. 

A  series  of  germination  experiments  in  a  sand  by  Stew- 
art (28)  showed  that  10,000  parts  per  million  of  sodium 
sulphate  was  generally  fatal  to  seeds  of  barley,  rye,  wheat, 
oats,  peas,  alfalfa,  and  red  and  white  clovers.  The  re- 


52  TOXIC  LIMITS  OF  ALKALI 

sistance  of  the  plants  was  about  in  the  order  given,  barley 
being  most  tolerant.  About  5000  parts  per  million  of 
sodium  carbonate  or  sodium  chloride  was  fatal  to  the 
germination  of  these  plants,  and,  excepting  that  peas 
were  the  most  resistant  to  sodium  carbonate  and  alfalfa 
was  weakest  for  those  salts,  the  order  of  toxicity  was 
about  as  .given  above. 

Oats  and  mustard  were  found  more  resistant  than  flax 
for  sodium  chloride  and  sodium  sulphate  in  pots  of  sand 
containing  315  to  1889  parts  per  million  of  these  salts. 
Some  influence  of  sodium  sulphate  was  perceptible  at  the 
higher  concentrations  and  the  sodium  chloride  caused 
injury  to  the  oats  and  mustard  in  the  larger  quantities. 
Wheat,  oats,  and  peas  failed  to  grow  in  soils  containing  390 
parts  per  million  of  chlorides  but  survived  in  the  presence 
of  10,000  parts  per  million  of  total  salts.  Wheat  and  oats 
could  withstand  20,000  parts  per  million  of  total  salts 
where  the  chlorine  content  was  less  than  1250  parts  per 
million. 

Claudel  and  Crochetelle  (12)  found  that  sodium  nitrate 
in  concentrations  of  2000  parts  per  million  prevented  the 
germination  of  buckwheat  and  beans,  injured  or  checked 
the  germination  of  beet  seed,  and  badly  injured  those  of 
clover.  However,  it  had  very  little  effect  on  wheat  and  bar- 
ley seed.  Buckwheat  was  considerably,  and  clover  slightly, 
affected  by  1000  parts  per  million.  Barley  was  the  only 
crop  able  to  withstand  5000  parts  per  million  of  this  salt. 

From  the  above  discussion  of  the  effects  of  alkali  in 
sand  on  plants,  it  is  seen  that  where  allowance  is  made  for 
the  difference  in  the  method  of  arriving  at  the  toxic  limits, 
the  results  are  fairly  uniform  when  compared  with  those 
of  solution  determinations.  The  two  salts,  sodium  car- 
bonate and  sodium  chloride,  are  nearly  the  same  in  toxicity, 


IN  LOAM   SOIL  53 

while  sodium  sulphate  is  considerably  less  harmful  than 
the  former  two  salts. 

In  Loam  Soil.  —  From  a  practical  point  of  view  loam 
soil  is  a  much  more  desirable  medium  for  studying  the 
effect  of  alkali  on  plants  than  is  either  sand  or  a  solution. 
Absorption,  antagonism,  and  physical  conditions  must 
all  eventually  be  taken  into  consideration  before  the  real 
toxic  effect  of  the  salts  under  normal  conditions  can  be 
arrived  at  correctly. 

The  use  of  loam,  or  other  soil  containing  organic  matter 
and  having  high  absorptive  properties,  complicates  the 
determination  of  the  toxicity  of  salts.  Harris  and  Pitt- 
man  (u)  found  that  of  two  soils  containing  equal  quantities 
of  alkali  and  equivalent  moisture  contents,  wheat  on  the 
soil  with  highest  organic  matter  was  injured  less  than 
where  the  organic  matter  was  about  as  it  is  in  ordinary 
loam.  The  organic  matter  appeared  to  remove  sodium 
carbonate  from  the  soil  solution  so  that  this  salt  appeared 
less  toxic  than  has  usually  been  ascribed  to  it  from  solu- 
tion or  sand  cultures  or  field  extraction  experiments. 
Wheat  plants  tolerated  more  alkali  in  a  loam  than  in  either 
a  sand  or  clay  and  more  in  a  coarse  loam  than  a  finer  one 
with  the  same  percentage  of  moisture,  although  with 
equivalent  moisture  contents  the  coarser  loam  was  less 
tolerant  than  the  finer.  The  toxicity  of  the  salts  de- 
creased with  increasing  percentages  of  soil  moisture  up 
to  the  maximum  moisture  content  producing  good  crops. 
Changing  the  moisture  relationship  of  the  soil  influenced 
the  toxicity  of  sodium  chloride  and  sodium  sulphate  more 
than  did  changing  the  organic  matter,  but  the  organic 
matter  had  the  greater  influence  for  sodium  carbonate. 
High  organic  matter  and  moisture  content  offered  the 
most  favorable  conditions  for  alkali  toleration. 


54  TOXIC  LIMITS  OF  ALKALI 

The  work  of  Haselhoff  (9)  on  heavy  loam  and  clay 
soils  led  him  to  conclude  that  because  these  soils  absorb 
chlorine  from  the  solutions  of  chlorides  and  thereby  gradu- 
ally destroy  the  physical  condition  of  the  soil,  the  injurious 
influence  of  chloride  solutions  on  soil  productiveness  and 
crop  yield  takes  place  gradually. 

Le  Clerc  and  Breazeale  (17)  found  the  greater  tolerance 
of  wheat  seedlings  to  sodium  chloride  in  clay  as  compared 


Trnrmrrnnr 


FtG.  7.  —  GROWTH  or  WHEAT  WITH  VARIOUS  CONCENTRATIONS 
OF  DIFFERENT  SALTS. 

to  sand  and  solution  cultures  to  be  due  to  the  lime  which 
the  clay  contained.  Shutt  (25)  found  that  calcium  oxide 
was  very  effective  and  calcium  carbonate  less  so  in  correct- 
ing the  toxicity  of  soil  containing  50,000  parts  per  million 
of  magnesium  sulphate.  Even  when  calcium  oxide  was 
used,  germination  was  still  retarded  but  a  larger  percent- 
age of  the  plants  grew  and  the  growth  was  more  healthy. 
This  antagonistic  action  of  calcium  and  other  salts  will 
be  taken  up  in  greater  detail  in  Chapter  VIII. 

In  the  work  done  on  the  germination  and  growth  of 
plants  in  Wyoming  by  Buffum  (2),  alkali  soils  were  leached 
of  their  alkali  and  then  made  up  to  the  required  percent- 


IN  LOAM  SOIL 


55 


age  by  the  addition  of  the  pure  salts  in  one  part  of  the 
experiment  and  in  the  other  the  soil  was  leached  of  a  por- 
tion of  its  alkali  sufficient  to  obtain  the  required  alkali 
content.  The  alkali  was  two-thirds  sodium  sulphate  and 
one-third  magnesium  sulphate  and  in  concentrations  from 
10,000  to  5o;ooo  parts  per  million.  The  test  showed  that 
in  a  soil  containing  25  per  cent  moisture,  rye  germinated 
almost  normally  with  22,500  parts  per  million  of  these 
salts;  barley  nearly  perfect  with  10,000  but  less  than  half 
normal  with  22,500  parts  per  million  in  the  natural  alkali 
soil;  wheat  about  two- thirds  normal  with  10,000  parts 
per  million;  alfalfa  perfect  with  10,000  parts  per  million 
but  producing  hardly  a  sprout  in  22,500  parts  per  million; 
while  turnips  and  oats  produced  less  than  one-half  normal 
germination  in  soil  containing  10,000  parts  per  million. 
The  time  taken  for  the  seeds  to  germinate  was  increased 
in  proportion  to  the  salt  present  even  for  the  lower  quan- 
tities of  alkali. 

Table  IX  summarizes  the  work  of  Guthrie  and  Helms  (7) 
in  a  rich  garden  loam  soil  mixed  with  nearly  an  equal 
quantity  of  light  sand. 

TABLE  IX.     CONCENTRATIONS  OF  SALTS  AFFECTING  THE  GROWTH 
OF  VARIOUS  CROPS 


'  SODIUM  CHLORIDE 

SODIUM  CARBONATE 

Wheat 

Barley 

Rye 

Wheat 

Barley 

Rye 

Germination  affected  
Germination  prevented  

Growth  affected 

500 
200O 

500 
2000 

IOOO 
2500 

IOOO 
2OOO 

IOOO 

4000 
1500 

200O 

3000 
5000 

IOOO 

4000 

2500 
6000 

1500 

4000 

2500 
5000 

2500 
4000 

Growth  prevented 

From  the  figures  it  is  seen  that  the  resistance  of  seed  to 
alkali  during  germination  is  not  always  the  same  as  the 


56 


TOXIC  LIMITS  OF  ALKALI 


resistance  during  later  growth,  and  the  relation  between 
germination  and  subsequent  growth  differs  for  these  two 
salts. 

With  the  following  quantities  of  alkali  added  to  loam 
soil  the  author  (10)  found  the  plants  indicated  in  the  table 
to  produce  about  half-normal  crops  of  dry  matter. 

TABLE  X.     QUANTITIES  OF  VARIOUS  SALTS  ADDED  TO  THE  SOIL 
WHICH  REDUCED  THE  YIELD  OF  CROPS  TO  ABOUT  HALF  NORMAL 


Crop 

Sodium  Chloride 

Sodium  Carbonate 

Sodium  Sulphate 

Barley 

^ooo 

IO  OOO 

Above  10  ooo 

Oats.            

4000 

8,000 

IO  OOO 

Wheat  
Alfalfa.  

3000 

•3000 

9,OOO 
6,OOO 

10,000 

IO  OOO 

Sugar-beets  

3000 

6,OOO 

JO,  OOO 

Corn  
Field  peas 

3000 

^ooo 

4,000 
4,000 

10,000 

9  ooo 

It  will  be  noted  that  the  figures  by  the  author  are  con- 
siderably above  those  of  Guthrie  and  Helms,  but  that  the 
carbonates  when  added  to  the  soil  in  each  case  were  less 
harmful  than  the  sodium  chloride.  In  the  sand  soil  the 
sodium  chloride  and  sodium  carbonate  were  noted  to  be 
nearly  equally  toxic  and  for  the  field  results  presented  in 
Chapter  XIV  the  sodium  carbonate  shows  nearly  the 
reverse  relationship  to  this.  The  low  toxicity  of  the 
salts  as  compared  with  those  for  field  determinations  are 
probably  due  partly  to  absorption  of  some  of  the  salts 
and  to  the  even  distribution  and  favorable  moisture  content 
possible  in  controlled  experiments  compared  with  field 
conditions.  Of  the  salts  used  in  the  experiments  of  the 
author  with  wheat  seedlings,  the  order  of  toxicity  for  salts 
added  from  highest  to  lowest  was  as  follows:  sodium 
chloride,  calcium  chloride,  potassium  chloride,  sodium  ni- 
trate, magnesium  chloride,  potassium  nitrate,  magnesium 


IN  LOAM  SOIL  57 

nitrate,  sodium  carbonate,  potassium  carbonate,  sodium 
sulphate,  potassium  sulphate,  and  magnesium  sulphate. 
This  order  does  not  hold  when  the  concentration  is 
determined  by  an  analysis  of  the  soil.  The  anions 
were  found  to  affect  the  toxicity  more  than  the  cation, 
the  chloride  being  the  most  toxic  anion  and  sodium  the 
most  toxic  cation. 

Bancroft  (i),  in  his  work  with  beans  growing  in  large 
pots  to  which  alkali  was  added  from  below  after  the  plants 
were  growing  until  they  wilted  and  died,  found  the  fol- 
lowing quantities  of  salts  just  killed  the  plants:  magnesium 
chloride,  2640  parts  per  million;  sodium  carbonate,  2710 
parts  per  million;  sodium  nitrate,  3700  parts  per  million; 
sodium  chloride,  5660  parts  per  million;  magnesium  sul- 
phate, 5820  parts  per  million;  sodium  sulphate,  6810  parts 
per  million;  and  sodium  bicarbonate,  12,300  parts  per 
million. 

In  germination  tests  on  sugar-beet  seed  by  Headden 
(Co'lo.  Sta.  Bui.  46)  it  was  found  that  while  1000  parts 
per  million  of  sodium  carbonate  permitted  the  seed  to 
germinate  freely,  5000  parts  per  million  was  injurious. 
The  limit  for  sodium  sulphate  was  about  8000  and  for  a 
mixture  of  the  two  about  the  same  as  the  sodium  carbonate. 

From  the  foregoing  discussion  of  the  various  experi- 
ments with  alkali  under  different  conditions  and  from  the 
results  given  in  Chapter  XIV  on  crops  for  alkali  land,  it 
is  seen  that  the  limits  vary  so  widely  because  of  the  dif- 
ferent methods  of  arriving  at  these  limits,  that  unless  the 
conditions  can  be  duplicated,  considerable  error  might 
result  from  estimates  secured  by  different  experimenters. 
The  estimates  under  field  conditions  would  be  expected 
to  range  through  a  wider  limit  because  of  the  complicated 
changes  within  the  soils  and  because  of  differences  in  de- 


58  TOXIC   LIMITS  OF  ALKALI 

termining  the  salts  in  the  soils.  With  laboratory  experi- 
ments, the  same  allowances  must  be  made  because  of  the 
various  complicating  factors  such  as  moisture  content, 
organic  matter,  antagonism  of  the  salts,  absorption,  and 
differences  in  tolerance  of  the  plants  at  different  times. 

REFERENCES 

1.  BANCROFT,  R.  L.    The  Alkali  Soils  of  Iowa.     Iowa  Sta.  Bui.  177 

(1918) 

2.  BREAZEALE,  J.  F.     Effect  of  the  Concentration  of  the  Nutrient  Solu- 

tion upon  Wheat  Cultures.     Science,  n.  ser.  22  (1905),  pp.  146-149. 

3.  BUFFUM,  B.  C.     Alkali.     Wyo.  Sta.  Bui.  29  (1896),  pp.  219-253. 

4.  BUFFUM,  B.  C.     Alkali  Studies,  III.     Wyo.  Sta.   Rpt.   1899,  p.  40. 

Also  Rpt.  for  1900. 

5.  COUPIN,  H.     On  the  Poisonous  Properties  ot  Compounds  of  Sodium, 

Potassium,  and  Ammonium.  Rev.  Gen.  Bot.  12  (1900),  No.  137, 
pp.  177-193-  (Abs.  E.  S.  R.  12,  pp.  717-718.) 

6.  COUPIN,  H.     On  the  Poisonous  Properties  of  Sodium  Chloride  and  Sea 

Waters  toward  Plants.  Rev.  Gen.  Bot.  10  (1898),  No.  113,  pp.  177- 
190,  figs.  3.  (Abs.  E.  S.  R.  n,  p.  24.) 

7.  GUTHRIE,  F.  B.,  and  HELMS,  R.     Pot  Experiments  to  Determine  the 

Limits  of  Endurance  of  Different  Farm  Crops  for  Certain  Injurious 
Substances.  Agr.  Gaz.  N.  S.  Wales,  14  (1903),  No.  2,  pp.  114-120. 
See  also  16  (1905). 

8.  HANSTEEN,  B.     The  Relation  of  Plants  to  Salts  in  Soils.     Nyt.  Mag. 

Naturvidensk.  47  (1909),  No.  2,  pp.  181-192.  (Abs.  E.  S.  R.  23, 
p.  28.) 

9.  HASELHOFF,  E.    The  Action  of  Chlorides  on  Soil  and  Plant.     Fiihling's 

Landw.  Ztg.,  64  (1915),  Nos.  19-20,  pp.  478-508.  (Abs.  E.  S.  R.  35, 
pp.  423-424.) 

10.  HARRIS,  F.  S.     Effect  of  Alkali  Salts  in  Soils  on  the  Germination  and 

Growth  of  Crops.     Jour.  Agr.  Res.  Vol.  5  (1915),  pp.  1-52. 

11.  HARRIS,  F.  S.,  and  PITTMAN,  D.  W.     Soil  Factors  Affecting  the  Toxic- 

ity  of  Alkali.     Jour.  Agr.  Res.  Vol.  15  (1918),  pp.  287-319. 

12.  HICKS,  G.  H.     The  Germination  of   Seeds  as  Affected  by  Certain 

Chemical  Fertilizers.     U.  S.  D.  A.  Div.  Bot.  Bui.  24  (1900),  p.  15. 

13.  KEARNEY,  T.  H.    The  Wilting  Coefficient  for  Plants  in  Alkali  Soils. 

U.  S.  D.  A.  Bur.  PL  Ind.  Cir.  109,  pp.  17-25. 

14.  KEARNEY,  T.  H.,  and  CAMERON,  F.  K.     The  Effect  upon    Seeding 

Plants  of  Certain  Components  of  Alkali  Soils.  U.  S.  D.  A.  Rpt.  ?if 
pp.  7-60. 


REFERENCES  59 

15.  KEARNEY,  T.  H.,  and  HARTER,  L.  L.    The  Comparative  Tolerance  of 

Various  Plants  for  the  Salts  in  Alkali  Soils.  U.  S.  D.  A.  Bur.  PI. 
Ind.  Bui.  113  (1907),  p.  18. 

16.  KOSSOVICH,  P.     Alkali    Soils:    Their    Influence    on    Plants    and    the 

Methods  of  Examining  Them.  Zhur.  Opuitn.  Agron.  (Jour.  Exp. 
Landw.),  4  (1903),  No.  i,  pp.  1-42.  (Abs.  E.  S.  R.  15,  p.  22.) 

17.  LE  CLERC,  J.  A.,  and  BREAZEALE,  J.  F.     The  Effect  of  Lime  upon  the 

Alkali  Tolerance  of  Wheat  Seedlings.  Orig.  Commun.,  8th  Internat. 
Cong.  Appl.  Chem.  (Washington  and  New  York),  26  (1912), 
Sect.  Vla-XIb,  app.  p.  135.  (Abs.  E.  S.  R.  29,  p.  322.) 

18.  LESAGE,  P.     The  Limits  of  Germination  of  Seeds  after  being  Placed 

in  Salt  Solution.  Compt.  Rend.  Acad.  Sci.  (Paris),  156  (1913), 
No.  7,  pp.  559-562.  (Abs.  E.  S.  R.  29,  p.  218.) 

19.  MAGOWAN,   FLORENCE   N.     The   Toxic    Effect   of    Certain  Common 

Salts  of  the  Soil  on  Plants.     Bot.  Gaz.  45  (1908),  No.  i,  pp.  45-49. 

20.  MARCHAL,  E.     Influence  of  Mineral  Salts  on  the  Production  of  Tuber- 

cle on  Pea  Roots.  Compt.  Rend.  Acad.  Sci.  (Paris),  133  (1901), 
No.  24,  pp.  1032-1033.  (Abs.  E.  S.  R.  13,  p.  1017.) 

21.  MICHEELS,  H.     The  Influence  of  Chlorides  and  Nitrates  of  Potassium 

and  Sodium  on  Germinating  Plants.  Internat.  Ztschr.  Phys.  Chem. 
Biol.  i  (1914),  Nos.  5-6,  pp.  412-419. 

22.  MIYAKE,  K.    The  Influence  of  Salts  Common  in  Alkali  Soils  upon  the 

Growth  of  the  Rice  Plant.  Jour.  Biol.  Chem.  16  (1913),  No.  2, 
pp.  235-263. 

23.  MIYAKE,  K.    The  Influence  of  Acids,  Alkalies,  and  Alkali  Salts  on  the 

Growth  of  Rice  Plants.  Trans.  Sopporo  Nat.  His.  Soc.  5  (1913), 
No.  i,  pp.  91-95;  abs.  in  Bot.  Cent.  126  (1914),  No.  22,, p.  588. 

(Abs.  E.  S.  R.  34,  P- 3i.) 

24.  REVEIL.     Recherches  de  physiologic  vegetale  de  Faction  des   poisons 

sur  les  plantes.     (Paris,  1865.) 

25.  SHUTT,   F.   T.     Alkaline   Soils   of   Canada.     Can.   Exp.   Farms    Rpt. 

1893,  pp.   135-140. 

26.  SIGMUND,   W.    Ueber   die    pjnwirkung    chemischer   agentien   auf   die 

Kiemung.     Landw.  versuchst.  47  (1896),  No.  2. 

27.  SLOSSON,  E.  E.,  and  BUFFUM,  B.  C.     Alkali   Studies,  III.    Wyo.  Sta. 

Bui.  39  (1898),  pp.  35-56. 

28.  STEWART,  J.     Effect  of  Alkali  on  Seed  Germination.     Utah  Sta.  Rpt. 

1898,  pp.  xxvi-xxxv. 

29.  TOTTTNGHAM,  W.  E.     A  Preliminary  Study  of  the  Influence  of  Chlorides 

on  the  Growth  of  Certain  Agricultural  Plants.  Jour.  Amer.  Soc. 
Agr.  ii  (1919),  No.  i,  pp.  1-32. 

30.  TRUE,  R.  H.    The  Toxic  Action  ot  Acids  and  Their  Sodium  Salts  on 

Lupines.  Amer.  Jour.  Sci.  4  ser.  9  (1900),  No.  51,  pp.  183-192. 
(Abs.  E.  S.  R.  12,  p.  1010.) 


CHAPTER  VI 

NATIVE  VEGETATION  AS  AN  INDICATOR   OF 
ALKALI 

IT  is  highly  desirable  that  the  prospective  landowner 
should,  by  studying  the  trees,  shrubs,  and  grasses,  be  able 
to  say  that  the  soil  is  deep,  well-drained,  fertile,  free  from 
injurious  properties,  and  capable  of  producing  profitable 
crops.  Upon  many  soils  the  native  plants  tend  to  group 
themselves  to  the  exclusion  of  nearly  all  other  species. 
Generally  when  such  grouping  occurs,  there  is  some  pecu- 
liarity of  the  soil  which  is  made  evident  by  such  grouping. 
The  luxuriant  growth  of  one  species  of  plant  to  the  exclu- 
sion, or  the  near  exclusion,  of  other  species  affords  an 
excellent  index  to  the  nature  of  the  soil. 

How  Plants  Indicate  the  Soil.  —  Certain  plants  in  arid 
regions  are  seldom  found  except  when  the  soil  contains 
alkali  salts.  Davy  investigating  in  California  (i)  states 
that  "  there  are  at  least  197  species  natives  of  California, 
which  are  restricted  to  alkali  soils."  Some  of  these  plants 
seem  to  thrive  only  when  some  particular  salt  is  present 
in  certain  strengths,  resenting  even  small  quantities  of 
other  salts.  Other  plants  do  well  in  the  presence  of  any  of 
the  alkali  salts  so  long  as  moisture  or  soil  conditions  are 
right.  In  each  portion  of  the  arid  region  may  be  found 
some  plants  which  indicate  extremely  large  quantities  of 
salts  when  found  alone.  They  indicate  that  so  much  alkali 
is  present  in  the  soil  that  the  land  is  worthless  for  agri- 

60 


HOW   PLANTS   INDICATE  THE   SOIL 


61 


cultural  plants  without  reclamation  methods  first  being 
applied. 

These  characteristic  plants  are  generally  recognized  by 
the  farmers  of  the  district  in  which  they  occur,  but  the  exact 
qualities  of  the  soil  and  the  possibilities  of  its  reclamation 
are  not  so  often  known.  The  kind  of  plant  also  varies 
considerably  even  within  relatively  short  distances  be- 


FIG.  8.  —  ALKALI  CRUSTS  AT  THE  SURFACE  PREVENTING  THE 
GROWTH  OF  PRACTICALLY  ALL  VEGETATION. 

cause  of  difference  in  soil  or  drainage.  Changes  in  climate 
or  altitude  also  influence  the  type  of  plant  that  indicates  a 
particular  type  of  soil. 

A  number  of  studies  of  the  characteristic  plants  of  alkali 
lands  have  been  made  together  with  the  kind  and  amounts 
of  alkali  present  in  soils  on  which  they  grew.  From  these 
studies  fairly  intelligent  conclusions  may  be  drawn  as  to 
the  kind  and  quantity  of  alkali  in  the  soil  without  making 
a  chemical  analysis. 

In  using  native  vegetation  to  indicate  the  alkalinity  of 
a  soil,  however,  it  is  essential  that  judgment  should  not  be 


62      NATIVE  VEGETATION  AS  AN  INDICATOR 

passed  when  only  a  few  scattered  or  stunted  plants  are 
found.  Generally  when  such  scattered  alkali-indicating 
individuals  are  found  the  soil  contains  some  alkali,  but  the 
quantity  is  not  clearly  indicated.  It  is  only  when  the 
plants  produce  a  vigorous  growth  and  occupy  the  land  to 
the  exclusion  of  non-resistant  —  if  not  all  other  species  of 
plants  —  that  they  may  be  taken  to  indicate  the  kind  and 
quantity  of  alkali  characteristic  of  their  species. 


FIG.  9.  —  ALKALI  LAND  WHICH  is  INDICATED  BY  THE  GROWTH 
OF  SHADSCALE. 

It  should  be  kept  in  mind  also  that  under  certain  condi- 
tions alkali-indicating  plants  may  grow  well  where  alkali 
may  not  be  present  in  quantities  injurious  to  general 
crops  and  that  non-resistant  plants  may  be  growing  well 
on  land  so  strongly  impregnated  with  alkali  that  farming 
would  be  practically  impossible  without  reclamation. 
Such  conditions  as  a  shallow  hardpan,  a  dry  sandy  layer 
of  soil,  or  other  conditions  which  cause  the  plants  to  suffer 
for  want  of  water,  as  they  do  when  in  the  presence  of  ex- 
cessive quantities  of  alkali,  may  allow  the  presence  of  the 
alkali- resistant  plants  in  abundance  to  the  exclusion  of 


ALKALI-INDICATING  PLANTS  63 

others.  On  the  other  hand,  shallow-rooted  plants  which 
cannot  endure  alkali  may  grow  luxuriantly  on  land  which 
contains  alkali  below  the  depth  to  which  its  roots  feed 
but  so  near  to  the  surface  that  when  farming  is  attempted 
the  land  may  soon  be  ruined.  The  latter  condition  is 
represented  by  the  Bear  River  Valley,  Utah,  where  sage 
brush,  rabbit  brush,  and  salt  grass  are  growing  on  land 
practically  free  from  alkali  in  the  upper  foot  or  so,  but  the 
soil  to  a  depth  of  six  feet  contains  from  6000  to  30,000  parts 
per  million  of  salts,  mostly  sodium  chloride.  This  salt  is 
quickly  concentrated  near  the  surface  when  irrigation  is 
practiced,  making  farming  impossible. 

Alkali-indicating  Plants.  —  Some  of  the  characteristic 
plants  of  the  western  part  of  the  United  States  which 
should,  when  present  as  a  luxuriant  growth  upon-  the  land, 
be  regarded  as  indicating  distinctly  alkali  soil,  or  soil 
which  should  be  looked  upon  with  suspicion  until  chemical 
analyses  of  it  have  been  made,  are  given  below. 

Well-defined  alkali-indicating  plants 

Inkweed,  or  saltwort  (Suaeda  spp.) 

Tussock  grass,  or  purple  top  (Sporobolus  airoides).     Torr. 

Bushy  samphire,  or  Kern  greasewood  (Allenrolfea  occidentals)  (S.  Wats.). 

O.  Ktze. 

Dwarf  samphire  (Salicornia  spp.) 
Greasewood  (Sarcobatus  vermiculatus) 

Alkali-heath  (Frankenia  grandifolia  campenstris) .     A.  Gray 
Spike  weed  (Hemizania  pungens) 

Little  rabbit  brush  (bushy  goldenrod)  (Isocoma  veneta)  H.  R.  K.  (A.  Gray) 
Arrow  or  irrigation  weed  (Pluchea  serviced)  (Nutt.).  Coville.  (Sometimes 

Pluchea  borealis) 

Salt-bush  or  shadscale  (Atriplex  confertifolia,  etc.) 
Kochia  or  white  sage  (Kochia  vestita) 
Salt-grass  (Distichlis  spicata).     Greene 
Cressa  (Cressa  cretica  truxillensis).     Choisy 
Rabbit  brush  (rayless  or  false  goldenrod)  (Chrysothamnns  spp.) 


64      NATIVE  VEGETATION  AS  AN  INDICATOR 

Alkali-indicating  plants  not  commonly  forming  the  major 
portion  of  alkali-land  vegetation 

Inhabiting  fhioist  saline  lands: 

Arrow  grass  (Triglochin  marilima  and  T.  palustris)  L.  (Across  continent) 
Alkali  meadow  grass  (Puccinellia  airoides.     Nutt.)     (Entire  west.     N.  Mex.- 

Mont.) 

Marsh  grass  (Spartina  gracilis.     Trin.)     (Oregon  to  Texas) 
Trailing   buttercup    (Halerpestes   cymbalaria.     Pursh.)     (Rocky   Mts.,   n. 

seacoast) 
Shooting  star  or  American  cowslip  (Dodecalheon  salinum.     Nels.)     (Western 

Wyoming,  Utah,  Idaho) 

Glaux  (Glaux  maritima.     L.)     (Subsaline  soil  west  of  Mississippi) 
Aster  (Aster  angustus.    T.  and  G.)     (Colorado  and  Utah  to  Minnesota) 
Aster  (Aster  pauciflorus.     Nutt.)     (New  Mexico,  Arizona,  Utah) 
Crepis  (Crepis  glauca.     T.  and  G.)     (West  of  Missouri  to  Nevada) 
Plowman's  wort  (Pluchea  camphorata)  (Coast  of  Florida  to  Texas) 
Mousetail   (Myosurus  apetalus.     Gay)     (Western  North  America) 
Valeria  (Valeriana  furfurescens.     Nels.)     (Colorado  and  Wyoming) 
Pyrrocoma  uniflora.     Greene.     (Montana  to  Colorado  and  Utah) 
Rush  (Stir PUS  nevadensis.    Wats.)     (Wyoming,  California) 
Tuber  bubrush  (Scirpus  paludosus) 

Inhabiting  soil  not  moist  at  the  surface: 

Bud-brush  (Artemisia  spinescens.     Eat.)     (Colorado  to  Montana  and  west) 
Aster  (Aster  zylorhiza.     Nutt.)     (Southcentral  Wyoming.     Naked,  clayey, 

saline) 
Pyrrocoma  lanceolata.     Greene     (Saskatchewan.     Northern  Colorado  and 

west  to  Nevada) 
Flaveria    angustifolia.     Pers.     (Eastern    Colorado    and    New    Mexico    to 

western  Texas) 
Pepper  grass  (Lepidium  montanum.     Nutt.)     (Montana  to  New  Mexico 

and  westward) 

Wild  barley  (Hordeum  nodosum.     L.)     (Arizona  to  Alaska) 
Wild  rye  (Elymus  salinus.    Jones)    (Wyoming  and  Utah.    Saline  situations) 
Goosefoot  or  pigweed  (Chenopodium  rubrum.     L.)     (Across  continent  north- 
ward) 

Goosefoot  or  pigweed  (Chenopodium  soccosum.    Nels.)    (Southern  Wyoming) 
Monolepsis  spp.     (Colorado  and  westward.     Saline  soils) 

Botanically,  probably  half  of   the   alkali-loving  plants 
belong  to  the  Chenopodiaceae,  or  goosefoot  family,  which 


DISCUSSION  OF  PLANTS  65 

includes  beets,  mangles,  samphire,  saltwort,  salt-bush,, 
and  greasewood.  Some  of  the  smaller  families  such  as 
Frankeniaceae,  Plumb  aginaceae,  Rhizophoraceae,  and  Tama- 
ricaceae  are  noted  for  the  alkali  resistance  of  most  of  the 
species.  Some  other  families,  notably  Gramineac,  Cru- 
ciferae,  and  Compositae,  contribute  some'  of  the  more 
important  plants  found  to  do  well  on  alkali  lands. 

Discussion  of  Plants.  —  "Inkweed,  or  saltwort,  is  a 
perennial  shrub  with  a  small,  fleshy,  stem-like  leaf.  Each 
winter  the  plant  dies  down  close  to  the  ground  leaving 
behind  a  dark-colored  bush"  (5).  It  is  found  on  some 
of  the  worst  alkali  lands  of  California  (i),  in  one  in- 
stance being  found  on  soil  containing  38,000  parts  per 
million  of  total  salt  in  the  top  foot  of  soil,  and  it  has 
been  found  growing  luxuriantly  with  as  high  as  32,000 
parts  per  million  of  total  salts  in  the  top  foot  of  soil. 
Where  growing  luxuriantly,  the  soil  has  been  found  to 
contain  837  parts  per  million  of  sodium  carbonate,  and 
3313  parts  per  million  of  sodium  sulphate  in  the  upper 
three  feet  of  soil.  It  thus  indicated  a  soil  with  a  high 
content  of  black  alkali.  Where  found  in  abundance  the 
soil  is  generally  of  a  heavy,  sandy-loam  or  a  clay-loam 
texture  occurring  on  low-lying  lands  and  reclaimable  only 
at  great  expense.  Because  of  the  presence  of  black  alkali 
the  soil  is  puddled  so  badly  that  rainwater  generally  evapo- 
rates from  it  before  it  will  penetrate.  When  found  on  the 
higher  lands,  the  soil  is  generally  underlain  with  a  hard- 
pan  near  the  surface. 

Tussock  grass  (Sporobolus  airoides)  sometimes  forms  a 
coarse,  matty  or  tree-like  growth,  the  trunks  of  which  are 
often  from  1 8  to  20  inches  high.  It  forms  feathery  purple 
panicles  in  late  summer  and  is  relished  by  stock  better 
than  most  any  other  native  alkali-resistant  plant.  Ani- 


66     NATIVE  VEGETATION  AS  AN  INDICATOR 

mals  eat  only  the  grass  part  of  the  plant  leaving  the  trunk- 
like  stems  behind.  It  is  a  good  alkali  indicator  for  the 
arid  Southwest,  but  is  not  common  north  of  the  4oth 
parallel,  or  about  the  center  of  Utah  and  Nevada.  It 
has  been  found  growing  in  a  soil  with  an  alkali  content 
of  31,190  parts  per  million  in  the  upper  four  feet,  although 
it  makes  its  best  growth  with  about  3000  parts  per  million 


FIG.  10.  —  GREASEWOOD  AND  SHADSCALE.    THESE  PLANTS 
INDICATE  ALKALI  IN  THE  SOIL. 

of  total  salts.  Of  the  separate  salts  in  soil  on  which  the 
plants  were  growing  vigorously,  the  following  amounts 
were  found: 

Sodium  carbonate 1437  parts  per  million 

Sodium  chloride 387  parts  per  million 

Sodium  sulphate 1227  parts  per  million 

It  has  been  found  growing  with  over  10,000  parts  per 
million  of  sodium  chloride  and  20,000  parts  per  million  of 
sodium  sulphate.  The  range  of  tolerance  is  great;  hence, 
scattered  individuals  should  not  be  taken  to  indicate  ex- 
cessive quantities  of  alkali,  although  when  thick  and 


DISCUSSION  OF  PLANTS  67 

vigorous,  especially  when  occurring  along  with  other 
alkali  indicators,  it  may  be  safe  to  call  the  land  unsuitable 
for  farming.  It  may  occur  on  dry  prairie  soils  where  very 
small  quantities  of  alkali  are  present. 

Kern  greasewood  or  bushy  samphire  (Allenrolfea  occi- 
dentalis)  is  a  shrubby  evergreen  bush  i  to  4  feet  in  height 
with  numerous  cylindrical,  fleshy,  practically  leafless 
alternating  branches,  and  with  a  large  taproot.  It  is 
nearly  always  found  on  the  low-lying,  and  generally  clayey, 
soils  with  a  plentiful  supply  of  moisture.  Soils  on  which 
it  does  well  are  usually  saturated  with  water  throughout 
the  growing  season,  but  may  become  "dry  bogs"  during 
part  of  the  year.  The  salt  content  of  such  soils  is  almost 
invariably  high,  sometimes  reaching  over  30,000  (i,  2) 
parts  per  million  of  total  salts  with  a  good  growth  of  the 
plant.  It  has  been  found  to  make  a  good  growth  in  the 
presence  of  300  parts  per  million  of  sodium  carbonate, 
13,000  parts  per  million  of  sodium  chloride,  and  17,000 
parts  per  million  of  sodium  sulphate.  It  grows  with  a 
higher  sodium  chloride  content  than  any  other  plant  known 
at  present.  Soils  on  which  this  plant  forms  the  major 
growth  are  usually  hopelessly  alkaline;  even  salt  bushes 
fail  on  the  soils  on  which  Allenrolfea  does  best.  The  heavy 
soils  make  reclamation  by  drainage  difficult  so  that  such 
soils  can  seldom  be  used  profitably. 

Dwarf  samphire  (Salicornia  subterminalis  and  other 
species)  is  a  nearly  leafless  plant  with  cylindrical,  fleshy, 
many-jointed,  opposite  branches.  All  soils  upon  which  it 
has  been  found  are  excessively  alkaline.  It  grows  well 
on  land  with  a  total  salt  content  of  27,000  (i,  2)  parts 
per  million  in  the  upper  four  feet.  Analyses  of  the  soil 
on  which  it  was  growing  well  showed  it  to  contain  757 
parts  per  million  of  sodium  carbonate,  7852  parts  per  mil- 


68      NATIVE  VEGETATION  AS  AN  INDICATOR 

lion  of  sodium  chloride,  and  19,627  parts  per  million  of 
sodium  sulphate.  Thus,  it  resists  larger  quantities  of 
sodium  chloride  and  sodium  sulphate  than  most  other 
plants.  Both  the  seashore  and  the  inland  species  indicate 
land  which  is  useless  for  farming  until  reclaimed  by  pro- 
longed draining,  which  in  many  cases  is  at  present  un- 
economical. 

Greasewood  (Sarcobatus  vermiculatus)  is  one  of  the  most 
common   alkali-indicating  plants   found   on   moist   saline 


FIG.  ii.  —  THE  BORDER  BETWEEN  GREASEWOOD  AND  SALT  GRASS. 
THE -LAND  INCREASES  IN  ALKALI  TOWARD  THE  SALT  GRASS. 

flats  of  the  intermountain  country.  Viewed  at  a  distance 
the  patches  of  greasewood  have  a  pleasant  bright-green 
color  decidedly  in  contrast  to  much  of  the  darker  or  gray- 
ish alkali  vegetation.  Besides  the  numerous  sharp  spines 
which  protect  the  small  fleshy  leaves  from  browsing  ani- 
mals, the  plant  is  bitter  and  salty  so  that  no  useful  animal 
will  eat  it.  Although  it  has  not  been  found  on  soil  con- 
taining more  than  8000  (4)  parts  per  million  of  total  salts 
in  the  upper  feet,  its  large  taproot  has  been  found  pene- 
trating soil  with  nearly  double  this  amount  of  salt  (mostly 


DISCUSSION  OF  PLANTS  69 

sodium  chloride).  Hilgard  (2)  reports  1170  parts  per 
million  of  sodium  carbonate,  230  parts  per  million  of 
sodium  chloride,  and  2260  parts  per  million  of  sodium 
sulphate  as  being  characteristic  quantities  of  the  common 
alkali  salts  present  where  the  plant  does  best  and  that  its 
presence  "invariably  indicates  a  heavy  impregnation  of 
land  with  black  alkali  or  carbonate  of  soda"  (2,  page  542). 
Although  the  latter  statement  is  generally  true,  it  has 
been  found  on  land  showing  only  sulphates,  and  Kearney 
and  others  (4)  found  it  growing  on  land  in  Utah  without 
sodium  carbonate  as  a  characteristic  salt.  Kearney  says 
it  is  not  an  infallible  alkali  indicator  as  it  was  found  making 
its  largest  and  thriftiest  growth  on  dunes  of  pure  sand. 
It  is  usually  associated  with  a  rich  silty  or  sandy  soil, 
moist  in  the  upper  foot  and  containing  excessive  quantities 
of  salts.  It  will  endure  larger  quantities  of  alkali  than 
most  alkali  plants.  Greasewood  soils  are  sometimes  too 
alkaline  to  permit  profitable  reclamation. 

Alkali-heath  (Frankenia  grandifolia  campenstris)  is  a 
perennial  herb  with  opposite .  or  clustered  simple  leaves 
and  with  a  deep-rooted,  flexible,  wiry,  rootstock.  It  is  a 
hardy  plant  which  often  persists  as  a  weed  on  cultivated 
land.  Although  it  generally  indicates  strong  alkali  where 
it  is  growing  luxuriantly,  it  will  grow  with  a  great  varia- 
tion in  alkali  content  —  from  about  200  to  31,000  (i,  2) 
parts  per  million  of  total  salts.  The  optimum  quantities 
found  by  Hilgard  (2)  ranged  from  about  4000  to  17,600 
parts  per  million  in  the  upper  four  feet  of  soil.  Of  this 
amount  43  to  1224  parts  per  million  was  sodium  carbonate, 
360  to  636  parts  per  million  sodium  chloride,  and  2158  to 
17,220  parts  per  million  sodium  sulphate.  Hilgard  re- 
gards land  that  grows  this  plant  to  be  unfit  for  crops  with- 
out reclamation,  although  Mackie  (5)  says  it  will  generally 


70      NATIVE  VEGETATION  AS  AN  INDICATOR 

contain  comparatively  small  quantities  of  alkali,  and 
"  where  this  bush  is  found  growing  uniformly  over  an  area 
to  the  exclusion  of  the  most  resistant  alkali  indicators, 
the  alkali  is  found  below  the  surface  from  i  to  3  feet  in  a 
free  sand  or  sandy  loam  soil.  This  "  land  yields  crops  "  of 
alfalfa  and  grain  or  orchards  and  can  be  kept  free  from 
injurious  quantities  of  alkali  by  proper  methods  of  irriga- 
tion and  drainage." 

Cressa  (Cressa  cretica  tmxillensis)  is  a  perennial  herb 
with  a  woody  base  from  which  many  leafy  branches  ex- 
tend. The  leaves  are  almost  sessile  and  are  characterized 
by  their  silky,  villous,  and  hairy  nature.  Cressa  is  a  com- 
mon sea-coast  plant  in  many  of  the  arid  parts  of  the  world. 
In  the  United  States  it  is  found  along  the  Texas  coast 
and  scattered  throughout  California,  extending  at  least 
to  the  Arizona  line.  Alkali-heath  has  been  found  growing 
with  a  higher  total  salt  content  than  Cressa,  but  Cressa  is 
a  surer  indicator  of  irreclaimable  alkali  land  because  the 
lower  limit  in  which  it  grows  is  much  higher.  Although 
sulphates  predominate  in  Cressa  soil,  it  will  be  noticed 
that  it  does  well  with  chlorides  in  quantities  dangerous 
to  ordinary  crops. 

Salt-bush,  or  Shadscale  (A triplex  spp.),  is  of  two  types  - 
the  perennial,  which  is  generally  bushy  or  shrubby,  and 
the  type  that  occurs  as  an  annual  weed.  The  leaves  are 
usually  alternate,  simple,  and  often  silvery,  scurfy,  or 
having  an  ashen-gray  color,  the  bush  type  often  being 
mistaken  for  sagebrush.  The  bush  belongs  to  the  same 
family  as  the  beet  and  it  can  readily  be  detected  by  its 
beet-like  seeds.  A  number  of  the  A  triplex  species  grow 
in  soil  which  contains  little  or  no  alkali,  but  the  moisture 
conditions  are  generally  unfavorable  on  any  soil  which 
has  a  vigorous  growth  of  them,  and  most  of  the  common 


DISCUSSION   OF   PLANTS 


71 


species  of  the  western  arid  country  produce  their  most 
luxuriant  growth  in  the  presence  of  dangerous  quantities 
of  alkali.  Land  upon  which  saltbush  —  either  bush  or 
weed  —  grows  best  is  generally  light  and  free  from  alkali 
in  the  top  foot  or  so;  but  is  underlain  by  heavier  soil  which 
is  likely  to  contain  large  quantities  of  alkali.  Such  soils 
are  seldom  underlain  by  hardpan  and  are  usually  porous 


FIG.  12.  —  THE  LAST  PLANT  TO  ABANDON  AN  ALKALI  FLAT 

so  that  they  may  be  reclaimed  »by  flooding.  Crops  can  as 
a  rule  be  grown  on  the  soil  on  which  saltbush  occurs,  but 
there  is  likely  to  be  a  rise  of  alkali  where  great  care  is  not 
taken  to  prevent  it.  The  alkali  is  likely  to  be  of  the  white 
type  entirely,  although  it  will  grow  with  as  much  as  1200 
parts  per  million  (2)  sodium  carbonate  in  the  soil.  The 
annual  A  triplexes  are  similar  to  the  bushes  in  color  and 
appearance  of  the  leaves  but  do  not  have  the  persistent 
woody  base  of  the  latter.  They  range  in  height  from 
about  i  to  4  feet.  Land  upon  which  A  triplex  forms  the 
principal  vegetation  should  be  looked  upon  with  suspicion 


72     NATIVE  VEGETATION  AS  AN  INDICATOR 

until  borings  and  analyses  show  it  to  be  free  from  alkali, 
unless  plans  are  laid  for  immediate  drainage.  Soils,  con- 
taining as  much  as  10,000  parts  per  million  (3)  of  salts  — 
mostly  sodium  chloride  —  but  with  the  upper  foot  or  so 
dry  and  free  from  alkali,  have  been  found  to  produce 
excellent  saltbushes.  They  grow  equally  well  in  the 
presence  of  nearly  8000  parts  per  million  (2)  of  sodium 
sulphate.  Because  of  the  porous,  dry,  upper  soil,  and  the 
tendency  to  have  alkali  beneath,  such  soils  are  ordinarily 
unfit  for  dry-farming. 

Kochia,  or  White  Sage  (Kochia  bestita),  is  a  low-lying 
shrub  with  its  branches  close  to  the  ground  and  with  a 
strong  taproot  which,  however,  seldom  penetrates  to  a 
greater  depth  than  one  foot.  New  shoots  are  sent  up  from 
its  roots.  Its  leaves  are  alternate,  sessile,  villous,  narrow, 
and  entire.  The  branches  as  well  as  the  leaves  are  fre- 
quently covered  with  short  woolly  hairs.  It  is  found  in  the 
intermountain  country  from  Colorado  to  Nevada.  Land 
upon  which  it  occurs  is  usually  free  from  injurious  salts 
in  the  upper  foot  or  so,  some  observations  showing  the 
upper  foot  to  contain  about  1200  parts  per  million  of  total 
salts  (4),  but  the  soil  beneath  which  its  roots  feed  is  almost 
invariably  impregnated  with  so  much  alkali  that  deeper 
rooting  plants,  such  as  the  sagebrush  (Artemesia  tridentata) 
cannot  exist.  Kochia  itself  is  not  alkali  resistant,  but 
where  it  exists  to  the  exclusion  of  sagebrush  and  similar 
nonresistant  plants  the  lower  depths  of  soil  are  either 
high  in  alkali  or  underlain  at  shallow  depths  with  a  hardpan 
which  prevents  deep  penetration  of  roots.  Either  con- 
dition makes  the  land  undesirable  for  general  farming  be- 
cause of  the  likelihood  of  a  rise  of  alkali.  Kochia  land 
frequently  contains  some  black  alkali  and  the  soil  is  often 
rather  impervious  so  that  reclamation  is  difficult. 


OTHER  PLANTS  73 

Salt-grass  (Distichlis  spicata)  occurs  throughout  the 
world,  being  the  most  common  plant  found  on  alkali  lands. 
It  grows  well  on  land  so  free  from  alkali  that  some  of  the 
common  alkali-loving  plants  such  as  greasewood  fail,  but 
can  withstand  and  make  a  good  growth  with  as  much  as 
24,000  parts  per  million  of  total  salts  fn  the  soil.  No 
preference  is  shown  for  any  of  the  alkali  salts.  The  high- 
est quantities  found  in  soil  on  which  it  grew  well  are  as 
follows : 

Sodium  carbonate 8517  parts  per  million 

Sodium  chloride 4398  parts  per  million 

Sodium  sulphate 2750  parts  per  million 

These  quantities  are  only  suggestive,  however,  as  great 
variations  are  found  wherever  the  grass  is  found.  It  is 
a  poor  indicator  of  alkali  either  quantitatively  or  quali- 
tatively, but  when  taken  together  with  other  plants  grow- 
ing with  it  something  of  the  nature  of  the  land  may  be 
indicated. 

Other  Plants.  —  A  number  of  other  plants  which  do 
well  on  alkali  soils,  but  which  are  not  so  distinctive  as  a 
general  rule,  are  the  following:  Rabbit  brush  or  false 
golden-rod  (Chrysothamnus  spp.)  which  is  cluster-flowered 
and  woody-based;  Plowman's  wort  (Pluchea  camphorata 
(i)  DC.),  a  spicy  or  salt  march  Fleabane  found  in  the 
marshes  of  Texas  and  Mexico  as  well  as  on  the  eastern 
and  southern  coast  of  the  United  States;  little  rabbit 
brush  (Isocoma  veneta  Grey)  a  perennial  composite  bush 
about  1 8  inches  high  with  a  sparse,  smooth,  dark-green 
foliage  usually  growing  in  deep  loamy  soils  with  a  medium 
salt  content;  spike  weed  (Hemizonia  pungens),  a  yellow- 
flowered  spiny  composite  which  grows  in  a  dense  mass 
to  the  exclusion  of  most  other  plants  on  comparatively 
weak  alkali  land  with  fair  drainage;  arrow  or  irrigation 


74     NATIVE  VEGETATION  AS  AN  INDICATOR 

weed  (Pleuchea  borealis),  a  composite  with  a  brush-like 
head  supported  on  a  stem  4  to  8  feet  high  which  tolerates 
a  limited  quantity  of  alkali  on  a  porous,  deep,  well-drained 
soil.  Plants  other  than  those  discussed  above  are  char- 
acteristic of  alkali  lands  in  their  respective  districts,  but 
sufficient  data  are  not  at  hand  to  determine  their  exact 
reliability  as  to  alkali  resistance.  Many  other  plants 


FIG.  13.  —  PLANTS  GROWING  AT  THE  TOP  OF  SAND  DUNES,  THE  ONLY 
PLACE  WHERE  THE  ALKALI  is  NOT  TOO  STRONG  FOR  PLANT  GROWTH. 

grow  upon  alkali  land  during  the  wet  season  when  the  soil 
solution  is  dilute,  but  none  of  them  can.be  classified  as 
distinctive  in  determining  soil  alkali  conditions. 

Description  of  Alkali-indicating  Plants.  —  Allenrolfea 
occidentalis  (Watson)  Kinitze.  —  Bushy  samphire  or  kern 
greasewood  is  a  shrubby  evergreen  bush  i  to  4  feet  high 
with  numerous  cylindrical,  jointed,  fleshy,  practically  leaf- 
less alternating  branches.  The  leaves  are  triangular  or 
scale-like  in  shape.  It  has  a  large  taproot  and  but  few 
lateral  roots.  Generally  found  in  low-lying  moist  lands 
from  the  40 th  parallel  southward,  the  northern  plants 


DESCRIPTION  OF  ALKALI-INDICATING  PLANTS     75 

generally  being  somewhat  more  dwarfed  than  those  farther 
southward. 

Artemesia  spinescens  (Eat.).  —  Bud  brush  has  the  woolly 
covering  and  the  general  appearance  of  common  sagebrush, 
but  is  dwarfed  —  4  to  16  inches  high  —  and  is  spiny. 
Found  throughout  the  West. 

Aster  angustus.  —  Perennial  herb  with  stems  4  to  12 
inches  high,  branching,  leafy.  It  has  the  typical  aster 
design  of  flowers,  but  they  are  smaller  with  the  corolla 
of  the  ray  flowers  reduced  to  the  tube  and  much  shorter 
than  the  elongated  style. 

Aster  pauciflorus.  —  Stems  8  to  10  inches  high  from  a 
slender  root-stock,  single  and  bearing  few  heads.  Leaves 
moderately  fleshy  and  elongated  in  shape. 

Aster  xylorhiza.  —  Perennial  with  deep-set  woody  roots 
supporting  several  or  solitary  stems.  The  heads  are  large 
with  conspicuous  white  rays.  Stems  leafy,  about  4  to  8 
inches  high,  terminating  in  a  short  flower  stalk. 

Atriplex.  —  Salt-bush  or  shadscale  (A triplex  spp.),  peren- 
nial and  annual  types  —  perennial  usually  bushy  or 
shrubby,  and  annual  usually  taller  and  more  weed-like. 
Leaves  generally  alternate,  simple,  and  often  silvery  or 
white  scurfy  or  having  an  ashen-gray  color.  Bush  is 
often  mistaken  for  sagebrush,  but  several  species  have 
spines  or  thorns. 

Crepis  glauca.  —  Perennial  herb  with  few  small  yellow 
flowers  borne  upon  a  leafless  or  practically  leafless  long 
stem.  It  is  from  8  to  24  inches  high  and  characterized 
by  its  covering  of  white  powdery  material  on  leaves  and 
elsewhere  and  lack  of  pubescence. 

Chrysothamnus  spp.  —  Rabbit  brush,  or  false  golden-rod, 
are  shrubby  plants  v;ith  woody  base  on  which  shoots 
holding  cylindrical,  often  hairy,  but  sometimes  resinous 


76      NATIVE  VEGETATION  AS  AN  INDICATOR 

leaves,  are  found.  Clusters  of  yellowish  flowers  like  those 
of  golden-rod  but  lacking  the  ray-flowers  around  the  margin 
of  the  clusters  as  in  the  golden-rod.  The  most  notable 
alkali-loving  species  of  this  group  is  Chrysothamnus  lini- 
folius,  which  is  found  along  wet  banks  of  alkali  streams; 
C.  Wyomingesis  and  C.  plattensis  are  found  more  on  alkali 
plains. 

Cressa  truxillensis .  —  A  perennial  herb  with  a  woody 
base  from  which  many  leafy  branches  extend.  The  leaves 
are  oblong  or  lance-shaped  with  very  short  stems,  silky, 
hoary,  or  villous  covering.  It  is  found  mostly  near  the 
seashore  in  Texas,  but  in  California  is  found  inland  through- 
out the  state. 

Distichlis  spicata.  —  Salt  grass  is  the  common  salt 
grass  of  alkali  soils. 

Dodecatheon  salinum.  —  Shooting  star  or  American  cow- 
slip has  a  short  crown  from  which  spring  numerous  slender 
matted  roots.  Leaves  about  i  inch  in  length,  wide-spread- 
ing or  ascending,  smooth,  and  rather  elliptic.  Flowers 
borne  upon  a  stem  about  4  to  8  inches  long  are  of  a  yel- 
lowish white  with  an  indistinct  purplish  ring  near  the 
base  and  has  segments  of  lilac-purple  in  places. 

Elymus  salinus  (Jones).  —  Wild  rye  is  a  coarse  perennial 
grass  with  flat  rough  leaves.  It  forms  in  dense  bunches 
of  rigid,  wiry  grass  standing  from  i  to  2  feet  high.  Found 
in  Utah  and  Wyoming  frequently  in  saline  places. 

Flaveria  angustifolia.  -  -  This  is  a  smooth-appearing 
herb  with  clusters  of  yellowish  flowers  and  opposite  stem- 
less  leaves.  It  is  8  to  20  inches  in  height. 

Frankenia  grandifolia.  —  Alkali-heath  is  a  perennial 
herb  with  a  woody  base  and  deep-rooted  flexible,  wiry, 
root-stocks.  Numerous  opposite  or  clustered  simple  rather 
thick,  lance-shaped  leaves  from  3  to  6  inches  long.  Largely 


DESCRIPTION  OF  ALKALI-INDICATING  PLANTS     77 

confined  to  the  Southwest  as  far  north  as  Arizona  and 
southern  Nevada. 

Glaux  maritima.  —  A  salt  marsh,  small  leafy-stemmed 
perennial  herb  propagated  by  slender  running  root-stocks. 
Stems  about  2  to  4  inches  high.  Leaves  oval-shaped. 
Flowers  purplish  or  white. 

Holer pestes  cymbalaria.  -  -  Trailing  buttercup  is  so  named 
because  of  long -join  ted  stolons  from  which  spring  new 
plants  at  each  node.  Low-growing,  rather  hairy,  with 
yellow  flowers  and  oblong  cylindrical  heads  of  fruit;  found 
in  moist  places.  Leaves  broadly  egg-shaped,  coarsely 
toothed  and  clustered  at  the  base  of  the  flower  stems  or 
nodes  of  the  stolons.  Flower  stem  2  to  4  inches  high. 

Hemizonia  pungens.  —  Spike-weed  is  a  yellow-flowered 
much-branched  spiny  composite  from  a  few  inches  to  2 
or  3  feet  high.  The  leaves  are  arranged  opposite  along 
hairy  or  bristly  branches.  Found  in  dense  patches  fre- 
quently to  the  exclusion  of  other  plants  on  well-drained 
generally  mildly  alkali  lands  of  southern  California. 

Hordeum  nodosum  (L.).  —  Wild  barley,  sometimes  called 
foxtail,  belongs  to  the  same  group  as  common  barley,  but 
is  seldom  taller  than  24  inches.  Has  a  narrow  spike  which 
is  usually  dark  green  or  purple,  and  is  awnless. 

Kochia.  —  White  sage  (Kochia  veftita),  dull  gray  plant 
about  5  to  6  inches  high  with  a  shrubby  base  and  roundish 
densely  hairy  leaves.  Viewed  at  a  distance,  bunches  give 
appearance  of  gray  blanket.  Flowers  solitary  or  few  in 
the  axils.  Ovary  oblong  nearly  equaling  the  calyx. 
Ripened  ovary  membranous.  Strong  taproot  to  about  i 
foot  deep. 

Lepidium  montanum  ( Nutt.).  —  Pepper  grass  is  a  smooth 
appearing  biennial  herb  with  small  white  petals.  The 
stems  spring  from  the  crown  of  the  thick  root  and  extend 


78     NATIVE  VEGETATION  AS  AN  INDICATOR 

to  a  distance  of  4  to  8  inches  from  the  base.  The  leaves 
are  toothed  or  have  numerous  leaflets  along  the  main  axis 
of  the  leaf. 

Myosurus  apetalus  (Gay) .  —  Mousetail  is  a  very  small 
annual  herb  with  a  tuft  of  spatulate  entire  leaves,  with  no 
apparent  stem,  surrounding  a  simple  solitary  five-petaled 
flower  borne  on  a  stem  i  to  2  inches  high.  It  is  found  in 
wet  saline  places  throughout  the  western  states. 

Pluchea  borealis.  —  Arrow,  or  irrigation,  weed  is  a  com- 
posite with  a  brushlike  head  supported  on  numerous 
hairy-covered,  silvery,  willow-like  branches  4  to  8  inches 
high.  Common  along  sandy  or  porous,  deep,  well-drained 
banks  of  streams  or  similar  soils  elsewhere. 

Pluchea  camphorata  (L)  DC.  —  Plowman's  wort  is  a 
spicy,  or  salt  marsh,  Fleabane  found  in  the  marshes  of 
Texas  and  Mexico. 

Pyrrocoma  (Null.).  —  Perennial  herbs  with  alternate 
leaves  and  showy  many-flowered  heads  of  yellow  flowers 
in  the  axils  of  the  upper  leaves  or  at  the  end  of  the  branch. 
Plants  generally  from  4  to  8  inches  high.  Found  through- 
out the  Rocky  Mountains. 

Salicornia  spp.  —  Dwarf  samphire  is  a  low  scaly-leafed 
but  nearly  leafless  fleshy  plant  with  cylindrical,  many- 
jointed  stems,  and*  opposite  branches.  Frequent  on 
saline  land  near  lakes  and  ponds. 

Sarcobatus  vermiculatus.  —  Greasewood  of  inter- 
mountain  country  found  on  moist  saline  flats,  patches  of 
which  generally  appear  a  much  brighter  green  than  most 
saline  vegetation  except  in  fall  when  it  changes  to  a  yel- 
lowish color.  It  has  numerous  sharp  spines  at  the  base 
of  which  are  small  fleshy  leaves  with  a  bitter  salty  taste. 
It  is  a  rigidly  branched  shrub  about  2  to  8  feet  high  with  a 
smooth  whitish  bark. 


DESCRIPTION  OF  ALKALI-INDICATING  PLANTS     79 

Scirpus  spp.  —  Rushes  are  tufted  plants  with  creeping 
root-stocks,  the  stem  sheathed  or  leafy  at  the  base  and  the 
spikelets  in  lateral  cluster.  Saline  soils  growing  these  plants 
are  generally  irreclaimable  without  considerable  expense. 

Spartina  gracilis.  —  Marsh  grass  is  a  perennial  with 
simple  and  rigid  slender  reed-like  stems  coming  from  ex- 
tensively creeping  scaly  root-stocks.  Stems  generally 
8  to  23  inches  high  and  somewhat  taller  than  the  spreading, 
two-ranked,  rough,  and  rigid  leaves  at  its  base.  Spikes 
4  to  10,  mostly  sessile,  closely  appressed  to  the  nearly 
smooth  rachis. 

Sporobolus  airoides.  —  Tussock  or  dropseed,  or  purple 
top  grass,  has  a  stout  coarse  and  rigid  base  or  trunk  often 
18  to  20  inches  high.  The  tufts  of  grass  are  often  i  to  3 
feet  in  height.  Open,  feathery,  pyramidal  panicles  with 
a  purplish  tinge  in  late  summer  are  borne  from  the  base 
trunk.  Leaves  smooth  beneath  but  harsh  above  and  taper 
gradually  from  base  to  a  fine  point  somewhat  rolled  in- 
wardly at  the  end. 

Suaeda  spp.  —  Inkweed,  or  saltwort,  perennial  shrub, 
with  small,  fleshy,  stem-like  leaves.  Growing  plants 
generally  i  to  2  feet  in  height  but  the  dark-colored  brush 
left  when  the  plant  ceases  growth  in  the  winter  lies  close 
to  the  surface  of  the  ground. 

Triglochin  maritima.  —  Arrow  grass  gives  the  appear- 
ance of  an  arrow  because  of  a  naked  jointless  stem  bearing 
an  arrowhead  shaped  greenish  flower  and  having  cylindri- 
cal rush-like  leaves  at  the  base  which  are  shorter  than  the 
flower  stem.  About  i  to  3  feet  in  height  and  rather  stout 
appearing.  T.  palustris  similar  to  above  but  seldom 
reaches  a  height  greater  than  i  foot  and  the  basal  leaves 
are  narrower  than  2  mm.,  while  leaves  of  above  are  from 
2  to  4  mm.  wide. 


80      NATIVE  VEGETATION  AS  AN  INDICATOR 

Valeriana  furfurescens  (Nels.). — The  roots  of  this 
plant  are  slender  and  peculiarly  scented,  leaves  entire, 
flowers  minute  and  numerous  with  greenish  yellow  corolla. 
Fruit  hairless,  rough,  and  scaly.  Found  mostly  in  saline 
meadow  lands. 

REFERENCES 

1.  DAVY,  J.  B.     Investigations  on  the  Native  Vegetation  of  Alkali  Land;-. 

Cal.  Sta.  Rpt.  1895-97,  pp.  53-75. 

2.  HILGARD,  E.  W.     Soils,  pp.  527-549.     (New  York,  1906.) 

3.  JENSEN,  C.  A.,  and  STRAHORN,  A.  T.     Soil  Survey  of  the  Bear  River 

Area,  Utah.     U.  S.  D.  A.  Bur.  Soils,  Field  Oper.  1904,  p.  27. 

4.  KEARNEY,  T.  H.,  BRIGGS,  L.  J.,  SHANTZ,  H.  L.,  McLANE,  J.  W.,  and 

PIEMERSEL,  1?.  L.     Indicator  Significance  of  Native  Vegetation  in 
Tooele  Valley,  Utah.     Jour.  Agr.  Res.  Vol.  i  (1914),  pp.  365-417. 

5.  MACKIE,  W.  W.     Reclamation  of  White-ash  Lands  Affected  with  Alkali 

at  Fresno,  California.     U.  S.  D.  A.  Bur.  Soils,  Bui.  42  (1907),  pp.  45- 

47- 

6.  MYERS,   H.    C.     Alkali   Lands   and   Sugar-beet   Culture.     Jour.    Soc. 

Chem.  Ind.  22  (1903),  pp.  782-785. 
Also  consult  standard  books  on  Botany. 


CHAPTER  VII 

CHEMICAL  METHODS   OF  DETERMINING 
ALKALI 

THERE  are  so  many  distinctly  different  methods  of 
making  chemical  analyses  of  soils  that  it  is  very  difficult 
to  compare  the  work  of  the  various  investigators  who  have 
studied  alkali  under  field  conditions.  The  wide  variations 
so  often  noted  between  results  of  investigators  in  different 
places  may  be  accounted  for  in  part  by  the  differences  in 
methods  of  determining  the  quantity  of  alkali  present. 
It  is  necessary  that  the  method  used  be  known  before  in- 
telligent interpretation  of  analyses  can  be  made.  In  the 
interest  of  uniformity  it  would  be  highly  desirable  to  adopt 
standard  methods.  Before  this  can  be  done,  it  will  be 
necessary  to  make  a  careful  study  of  the  various  methods 
in  order  that  the  best  one  to  secure  uniformly  accurate 
results  may  be  chosen. 

Preparing  the  Solution.  —  Probably  the  greatest  varia- 
tion in  methods  of  analyzing  alkali  soil  is  found  in  making 
the  soil  extract.  The  soluble  salts  are  dissolved  with  water 
and  not  with  the  stronger  dissolving  agents  that  are  used 
in  making  a  complete  analysis  of  a  soil,  since  it  is  the 
water-soluble  salts  that  come  under  the  designation  of 
alkali.  The  principal  variation  in  methods  consists  in 
the  relative  quantities  of  water  and  soil  used,  the  time  of 
agitation,  the  time  allowed  for  settling,  and  the  method  of 
filtering.  There  are  certain  other  methods,  such  as  ex- 

81 


82          METHODS  OF  DETERMINING  ALKALI 

trading  the  solutions  with  oil  or  by  pressure  or  centrif- 
ugal force,  which  are  not  in  general  use  as  yet,  the  great 
drawback  being  that  little  more  than  the  free  water  can 
be  obtained. 

King  and  his  associates  in  their  studies  of  soil  nitrates 
used  a  method  which,  with  a  number  of  amendments,  has 
been  used  extensively  by  later  investigators.  Schreiner 
and  Failyer  (9)  describe  a  modification  of  this  method 
which  has  probably  been  used  more  widely  than  any  other. 
They  discuss  it  as  follows: 

"If  comparable  results  are  to  be  obtained,  it  is  essential 
in  preparing  the  soil  extract  to  follow  as  nearly  as  practical 
a  uniform  procedure.  The  volume  of  water  used  and  the 
time  of  its  action  are  necessarily  conventional.  The  ratio 
of  five  parts  of  water  to  one  part  of  soil  has  been  adopted 
in  procuring  solutions  of  the  readily  water-soluble  salts 
in  many  of  the  soil  studies.  The  mixture  is  agitated  three 
minutes  and  allowed  to  stand  twenty  minutes  before 
filtering.  The  exact  procedure  when  the  soil  to  be  ex- 
amined is  still  in  the  moist  state  as  collected  in  the  field 
varies  slightly  from  that  when  it  is  air-dried  or  oven- 
dried.  All  results,  however,  are  stated  on  a  uniform  basis, 
preferably  on  the  dry  soil.  The  results  from  a  moist  soil 
are  not  comparable  with  those  obtained  from  a  dried  soil, 
although  both  be  stated  in  terms  of  dry  soil,  owing  to  the 
fact  that  dried  soils  give  a  somewhat  greater  concentra- 
tion of  soluble  salts  in  the  soil  extract. 

"From  Moist  Soil.  —  The  moist  samples  taken  from 
typical  and  comparable  portions  of  the  field  are  well  broken 
up  and  mixed  in  a  granite- ware  basin  or  porcelain  dish. 
Two  loo-gram  portions  of  this  composite  are  then  weighed 
out  on  a  balance  capable  of  weighing  accurately  to  within 
o.i  gram.  One  of  these  portions  is  for  the  moisture  de- 


FROM  MOIST  SOIL  83 

termination.  It  is  thoroughly  dried  in  an  oven  and  the 
content  of  moisture  thus  obtained  taken  into  consideration, 
if  the  results  of  the  analyses  of  the  solution  are  to  be  ex- 
pressed in  terms  of  the  dry  soil.  The  calculation  to  parts 
per  million  of  dry  soil  is  readily  made  by  means  of  the 
following  formula: 

s  =  5(500  +  W)^ 
(100  -  W)9 

where  5*  is  the  parts  per  million  of  the  dry  soil,  s  the  parts 
per  million  of  the  soil  solution  as  found  by  analysis,  and 
W  is  the  amount  of  moisture  in  grams,  in  the  100  grams 
of  the  moist  soil  sample  used  in  making  the  solution  as 
described  below.  If  it  should  be  desired  to  calculate  the 
strength  in  parts  per  million  of  the  actual  soil  moisture  as 
found  in  the  above  moisture  determination,  the  following 
formula  is  applied: 

5(500  +  W) 

JVL    =   > 

W 

where  M  is  the  parts  per  million  of  the  soil  moisture,  5  and 
IF  as  in  the  previous  formula. 

"  Measure  out  500  cc.  of  water,  and  after  transferring 
the  other  loo-gram  portion  of  the  moist  soil  to  a  mortar 
add  enough  of  the  water  to  make  a  thick  paste,  working 
well  with  the  pestle  so  as  to  break  down  all  granulations 
and  to  have  the  soil  well  puddled.  The  balance  of  the 
500  cc.  of  water  is  then  added  and  the  mixture  well  stirred 
with  the  pestle  during  three  minutes.  If  more  samples 
are  to  be  worked  in  the  mortar,  the  mixture  is  transferred 
to  a  jar  and  is  allowed  to  stand  twenty  minutes,  during 
which  the  coarser  particles  settle.  The  supernatant 
turbid  liquid  is  then  poured  into  one  of  the  filtering  cham- 


84         METHODS  OF  DETERMINING  ALKALI 

bers  fitted  up  with  a  well-washed  Pasteur-Chamberland 
filter  tube. 

"  From  Dry  Soil.  —  If  the  soil'  sample  to  be  used  is  al- 
ready air-dry  and*it  is  desired  to  give  the  results  in  terms 
of  the  completely  dried  soil,  it  will  be  necessary  to  de- 
termine the  amount  of  moisture  still  present  by  heating 
a  loo-gram  portion  in  the  drying  oven  and  making  the 
proper  allowance  in  the  final  calculation,  using  the  formula 
given  above.  If  the  soil  to  be  examined  is  oven-dried 
the  whole  composite  is  removed  from  the  oven  while  hot 
and  pulverized  in  a  large  mortar,  screening  through  a 
2-mm.  seive.  A  loo-gram  sample  is  then  weighed  out 
and  poured  into  a  glass-stoppered  bottle.  Add  500  cc. 
of  distilled  water  to  the  soil  in  the  bottle  and  shake  vigor- 
ously for  three  minutes  to  insure  a  thorough  puddling  of 
the  soil  particles.  The  mixture  is  allowed  to  stand  twenty 
minutes  for  the  coarser  particles  to  subside  and  is  then 
filtered.  The  mortar  may  be  used  as  described  above, 
but  it  is  more  convenient  to  use  the  shaking  bottle  when 
working  with  dry  pulverulent  soils." 

Methods  differing  from  the  above  for  extracting  soil 
solutions,  as  summarized  by  Hare  (7)  are:  the  Arizona 
method  in  which  50  grams  of  soil  are  added  to  800  cc. 
of  water  and  heated  on  a  water  bath  for  10  hours  when 
enough  water  is  added  to  make  the  solution  up  to  1000  cc. 
and  the  solution  allowed  to  stand  over  night  before  being 
filtered;  the  California  method  in  which  150  grams  of  soil 
are  added  to  300  cc.  of  water  and  after  shaking  allowed  to 
stand  1 2- hours;  the  Montana  method  in  which  50  grams 
of  soil  are  added  to  500  cc.  of  water,  shaken  and  allowed 
to  stand  over  night;  the  Texas  method  in  which  200  grams 
of  soil  are  added  to  1000  parts  of  water  and  shaken  oc- 
casionally for  2  hours;  and  the  Utah  methods,  in  the 


COMPARISON   OF    RESULTS 


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86          METHODS  OF  DETERMINING  ALKALI 

first  of  which  50  grams  of  soil  are  added  to  500  cc.  of  water 
and  in  one  case  agitated  for  5  minutes,  and  in  the  other 
case  shaken  intermittently  for  24  hours,  while  in  the 
second  method  50  grams  of  soil  are  added  to  1000  parts 
of  water  and  after  shaking  for  8  hours  allowed  to  stand  over 
night. 

From  comparisons  of  methods  at  the  Utah  Station,  the 
proportion  of  soil  to  water  influenced  the  quantity  of 
carbonate  found,  but  had  little  or  no  influence  on  chlorides 
or  sulphates. 

After  the  solution  has  been  in  contact  with  the  soil 
for  the  desired  length  of  time,  it  is  poured  into  a  Pasteur- 
Chamberland  filter  and  filtered  under  an  air  pressure  of 
30  to  40  pounds  per  square  inch.  The  first  50  to  200  cc. 
of  the  filtered  solution  are  discarded,  after  which  the  desired 
quantity  is  collected  and  bottled  until  needed  for  making 
the  tests  of  the  different  constituents. 

Determining  Total  Solids.  -  -  The  ordinary  method  of 
determining  the  total  soluble  salts  in  the  extracted  solu- 
tions is  to  evaporate  20  to  50  cc.  of  the  solution  to  dryness 
in  a  weighed  evaporating  dish  over  a  sand  or  steam  bath. 
Some  chemists  gently  ignite  the  residue  further  to  purify 
the  salts  of  undesirable  material,  while  some  re-dissolve 
the  residue  to  get  the  soluble  alkali  salts  and  help  eliminate 
calcium  and  magnesium  salts.  The  Bureau  of  Soils  does 
not  determine  the  total  salts  by  evaporation  and  declares 
it  to  be  unreliable. 

In  Table  XI  is  shown  the  total  salts  and  the  various 
constituents  of  alkali  as  determined  by  the  different 
methods  on  alkali  soils  in  Arizona  (12). 

Carbonate  and  Bicarbonate  Determination.  -  -  The 
method  for  determining  the  carbonate  and  bicarbonate 
used  by  the  Bureau  of  Soils  (9)  is  described  as  follows: 


CARBONATES    AND    BICARBONATES  87 

"One  portion  of  the  solution  will  serve  for  the  determina- 
tion of  both  carbonate  and  bicarbonate.  The  method 
depends  upon  the  different  actions  of  phenolphthalein 
and  methyl  orange  in  the  neutralization  of  these  two 
substances.  Potassium  hydrogen  sulphate  solution  is 
used  for  titrating,  the  first  step  being  the  phenolphthalein 
as  indicator.  The  reaction  is  expressed  by  the  following 
equation : 

Na2C03  +  KHS04  =  KNaSO4  +  NaHCO3. 

The  point  of  neutrality  is  shown  when  all  carbonate  present 
is  converted  into  bicarbonate.  The  second  step  is  the 
titration  of  the  bicarbonate  formed  in  the  first  step  to- 
gether with  that  existing  originally  in  the  solution,  using 
methyl  orange  as  indicator.  This  reaction  is  expressed 
by  the  following  equation: 

NaHC03  +  KHSO4  =  KNaS04  +  H2C03. 

The  point  of  neutrality  is  shown  in  this  case  when  all 
bicarbonate  has  been  decomposed."  The  total  titration 
for  bicarbonate,  less  the  titration  for  the  carbonate,  gives 
the  titration  for  the  bicarbonate  originally  present, 

This  and  certain  other  methods  for  determining  car- 
bonates does  not  always  prove  satisfactory  as  it  does  not 
distinguish  between  the  sodium  and  the  noninjurious 
calcium  and  magnesium  salts. 

The  New  Mexico  Station  uses  the  above  method  for 
determining  the  carbonates,  but  also  determines  the 
calcium  and  magnesium  and  combines  these  bases  with 
carbonates  before  determining  the  sodium  salts  of  the 
carbonate  radical.  With  the  exception  that  sulphuric 
acid  is  used  in  the  place  of  potassium  acid  sulphate  and 
that  methyl  orange  is  the  indicator,  this  is  also  one  of  the 
methods  used  in  Utah. 


88          METHODS  OF  DETERMINING  ALKALI 

In  the  work  at  California  no  distinction  has  been  made 
between  the  carbonate  and  the  bicarbonate  of  soda.  Their 
method  of  first  evaporating  the  solution,  then  igniting 
the  residue,  and  finally  redissolving  the  salts  before 
titrating  with  sulphuric  acid,  using  methyl  orange  as  the 
indicator,  eliminates  most  of  the  calcium  and  magnesium. 
After  this  the  solution  is  titrated  with  sulphuric  acid,  and 
the  difference  between  the  sodium  carbonate  added  and 
that  indicated  by  the  titration  shows  the  sodium  carbon- 
ate present  originally.  If  there  is  a  deficit,  the  quantity 
of  calcium  and  magnesium  carbonate  in  excess  is  shown. 

Acting  on  the  assumption  that  all  carbonates  and  bi- 
carbonates  were  combined  with  sodium  when  in  the  soil, 
the  Utah  Station  titrates  the  original  solution  with  sul- 
phuric acid  and  states  the  results  as  sodium  carbonate. 
Where  the  solution  remains  in  contact  with  the  soil  but 
a  few  minutes,  it  is  assumed  that  the  less  soluble  lime  and 
magnesium  salts  will  be  present  to  only  a  slight  extent, 
but  where  the  agitation  is  continued  for  Jong  the  results 
are  high  compared  with  other  methods  on  account  of  the 
presence  of  carbonate  other  than  those  of  sodium. 

Chloride  Determination. -- The  method  used  in  prac- 
tically all  places  for  determining  chloride  is  to  titrate  10 
to  50  cc.  of  the  original  solution  with  standard  silver 
nitrate  solution,  using  potassium  chromate  as  the  indicator. 
The  results  are  expressed  as  the  sodium  salt.  As  shown 
in  Table  XI,  the  results  by  the  different  methods  are 
fairly  uniform,  although  by  heating  to  get  the  solution, 
as  is  done  by  the  Arizona  method,  the  results  are  some- 
what higher  in  most  cases  than  with  the  other  methods. 
An  excess  of  silver  nitrate  titrated  back  with  ammonium 
sulfocyanide  is  sometimes  used,  but  it  is  rather  hard  to 
read  in  brown  solutions.  The  turbidity  method  for 
chlorides  is  little  used. 


NITRATE  DETERMINATION  89 

Sulphate  Determination.  —  The  most  common  method 
in  use  for  determining  sulphates  is  to  acidify  the  solution 
with  a  few  drops  of  hydrochloric  acid  and  after  bringing 
the  solution  to  boiling,  to  add  a  few  cubic  centimeters  of 
boiling  standard  barium  chloride.  The  solution  is  kept 
boiling  for  about  an  hour  and  then  filtered  through  an 
ordinary  filter  paper  and  the  precipitate  thoroughly  washed 
with  hot  water.  -  The  precipitate  and  the  filter  paper  are 
then  placed  in  a  weighed  crucible  which  is  heated  until 
all  volatile  matter  is  driven  off.  After  this  the  crucible  is 
reweighed  and  the  difference  as  barium  sulphate  calculated 
first  to  calcium  and  magnesium  and  the  remainder  to 
sodium,  if  the  former  bases  have  been  determined,  but 
otherwise  the  sulphates  are  all  expressed  as  sodium 
sulphate. 

Turbidity  and  colorimetric  methods  for  sulphate  de- 
termination have  been  employed  to  a  slight  extent,  but 
they  are  not  in  common  use.  In  certain  places,  notably 
at  the  California  Station,  the  difference  between  the  total 
solids  and  the  sum  of  the  carbonates  and  the  chlorides 
has  been  expressed  as  sodium  sulphate.  As  the  sulphates 
are  least  harmful,  and  in  certain  localities  seldom  present 
in  injurious  quantities,  they  are  frequently  omitted  from 
analyses  of  alkali. 

Nitrate  Determination.  —  Nitrates  are  seldom  deter- 
mined in  alkali  investigations,  but  under  a  few  conditions 
such  as  prevail  in  parts  of  Colorado  and  Utah,  they  reach 
toxic  concentrations,  and  it  is  therefore  desirable  that  the 
quantity  present  be  known.  The  method  for  nitrate  de- 
termination, which  has  been  most  extensively  used  in  the 
past,  is  discussed  by  Schreiner  and  Failyer  (9)  as  follows: 

"The  nitrates  are  best  determined  by  means  of  the 
color  produced  by  the  action  of  phenoldisulphonic  acid 


90          METHODS  OF  DETERMINING  ALKALI 

and  making  alkaline  with  ammonia.  Chlorides,  when 
present  in  considerable  quantities,  interfere  quite  markedly 
with  the  determination  of  nitrates  and  must  be  previously 
removed.  This  is  best  accomplished  by  means  of  silver 
sulphate  free  from  nitrates.  This  can  be  added  in  the 
solid  form,  thus  avoiding  dilution  of  the  original  solution. 
The  silver  sulphate  is  tested  for  nitrates  by  treating  some 
of  the  solid  salt  with  the  phenoldisulphonic  acid  reagent, 
diluting  with  water  and  adding  ammonia  water.  No 
yellow  color  should  be  produced.  The  silver  sulphate  as 
found  in  the  market  frequently  contains  nitrates  in  amounts 
sufficient  to  vitiate  all  results,  and  it  is,  therefore,  advis- 
able to  prepare  it  specially  for  this  work. 

"The  presence  of  some  kinds  of  organic  matter  also  in- 
terferes seriously  with  the  determination  of  nitrates  by 
this  method.  In  some  cases  it  is  the  foreign  color  only 
which  is  produced  by  the  strong  acid,  but  often  the  action 
is  of  more  vital  importance,  as  a  considerable  loss  of  nitrates 
occurs,  possibly  due  to  oxidation  of  the  organic  matter 
by  the  nitrate  instead  of  the  nitration  of  the  phenoldisul- 
phonic acid.  In  some  cases  it  is  advisable  to  reduce  the 
nitrates  to  ammonia  by  means  of  the  copper-zinc  couple. 
The  ammonia  is  distilled  off  and  determined  colorimetric- 
ally.  The  ammonia  originally  present  in  the  solution 
must  be  determined  separately  and  deducted.  Nitrites 
are  likewise  reduced  to  ammonia  and  must  be  allowed  for 
if  present. 

"  Analytical  Process.  —  Evaporate  50  cc.,  or  other 
convenient  quantity,  depending  upon  the  amount  of 
nitrate  present,  to  dryness  in  a  porcelain  dish  on  a  water 
bath,  removing  the  dish  as  soon  as  it  is  completely  dry. 
Add  i  cc.  of  the  phenoldisulphonic  acid  reagent  and  stir 
thoroughly  with  the  rounded  end  of  a  glass  rod  so  as  to 


ANALYTICAL  PROCESS  91 

loosen  the  residue  and  bring  the  acid  well  in  contact  with 
every  portion  of  it.  The  time  of  action  on  the  nitrate 
should  be  about  ten  minutes.  At  the  end  of  this  time  the 
acid  is  diluted  with  about  15  cc.  of  water  and  made  al- 
kaline with  ammonium  hydroxide,  a  yellow  color  being 
deyeloped  when  the  solution  becomes  alkaline.  This  is 
then  diluted  to  50  cc.  or  100  cc.  and  compared  with  the 
standard  colorimetric  solution.  If  the  color  is  too  in- 
tense for  direct  comparison  with  this  standard,  an  aliquot 
portion  may  be  taken  and  diluted  to  definite  volume  and 
the  strength  of  this  determined." 

To  clear  the  soil  extracts,  Greaves  and  Hirst  (6)  found 
the  following  methods  to  give  good  results:  The  addition 
of  2  grams  of  lime,  ferric  sulphate,  ferric  alum,  sodium 
alum,  or  potassium  alum  to  the  soil- water  mixture;  filter- 
ing through  Pasteur-Chamberland  filter,  or  centrifuging. 

To  eliminate  possible  error  due  to  the  presence  of  chlo- 
rides or  other  inorganic  materials,  certain  reduction 
methods  have  given  better  results  than  the  above  method. 
The  iron  reduction  method,  as  described  below,  was  found 
by  Greaves  and  Hirst  (6)  to  give  more  satisfactory  results 
in  the  presence  of  inorganic  salts  and  in  the  presence  of 
organic  matter  than  did  other  methods.  The  soil  is  first 
agitated  for  five  minutes  with  five  times  its  weight  of  water 
and  clarified  by  one  of  the  methods  described  above,  prefer- 
ably with  alum. 

"An  aliquot  part  (100  cc.)  of  the  supernatant  liquid  is 
pipetted  off,  and,  together  with  2  cc.  of  a  saturated  solu- 
tion of  sodium  hydroxide,  evaporated  to  about  one-fourth 
of  its  original  volume  to  free  from  ammonia.  If  urea  is 
present,  it  is  necessary  to  evaporate  to  dryness.  To  this 
is  added  50  cc.  of  ammonia-free  water,  5  grams  of  'iron- 
by-hydrogen,'  and  30  cc.  of  sulphuric  acid  (sp.  gr.  1.35). 


92          METHODS  OF  DETERMINING  ALKALI 

If  less  than  40  mg.  of  nitric  nitrogen  is  to  be  determined, 
it  is  well  to  take  a  correspondingly  smaller  quantity  of 
iron  and  sulphuric  acid.  The  neck  of  the  reduction  flask 
is  fitted  with  a  2-hole  stopper  through  which  passes  a 
50-cc.  separatory  funnel  and  a  bent  tube  which  dips  into 
a  vessel  containing  water  to  prevent  mechanical  loss. 
The  acid  is  slowly  added  and  allowed  to  stand  until  the 
rapid  evolution  of  hydrogen  is  over  and  then  heated  to 
boiling  for  ten  minutes.  The  contents  of  the  side  vessel 
should  be  returned  to  the  reduction  flask  before  the  re- 
action is  complete,  thus  insuring  the  complete  reduction 
of  any  nitrates  which  may  have  been  carried  over  with 
the  first  violent  evolution  of  the  hydrogen.  The  contents 
of  the  reduction  flask  are  transferred  to  a  Kjeldahl  flask, 
neutralized  with  sodium  hydroxide,  and  distilled  into 
standard  acid.  The  excess  of  acid  is  titrated  back  with 
standard  alkali,  lacmoid  being  used  as  indicator." 

Nitrates  should  be  determined  immediately  after  sam- 
pling unless  some  sterilizing  material,  such  as  chloroform, 
is  added  to  check  bacterial  activity. 

Determination  of  Bases.  —  Calcium.  --The  common 
method  for  determining  calcium  is  to  heat  a  given 
quantity  of  the  solution  nearly  to  boiling,  and,  after 
adding  a  few  drops  of  ammonia,  to  precipitate  the 
calcium  completely  by  adding,  drop  by  drop,  a  hot 
solution  of  ammonium  oxalate.  The  solution  is  kept 
at  this  temperature  for  about  2  hours  after  which  two 
or  three  decantations  with  hot  water  from  the  beaker 
containing  the  solution  are  passed  through  a  filter.  The 
precipitate  remaining  in  the  beaker  is  dissolved  with  a  few 
drops  of  hydrochloric  acid,  water  is  added,  and  the  former 
process  of  adding  ammonia  and  ammonium  oxalate  to 
reprecipitate  the  calcium  is  repeated.  The  solution,  to- 


DETERMINATION  OF  BASES  93 

gether  with  the  precipitate,  is  then  poured  onto  the  same 
niter  paper  as  before  and  thoroughly  washed  with  hot 
water.  Transfer  paper  to  original  beaker  containing  hot 
1:10  sulphuric  acid.  After  the  paper  has  been  immersed 
in  the  liquid  it  is  brought  up  on  the  side  of  the  beaker  by 
means  of  a  glass  rod.  Then  the  solution  is  titrated  to  the 
end  point  with  potassium  permanganate.  The  paper  is 
now  put  back  into  the  liquid  and  the  titration  finished. 
Some  prefer  to  ignite  to  constant  weight  the  precipitate 
left  on  the  filter  paper  and  calculate  it  as  calcium  oxide. 

Magnesium.  —  Usually  magnesium  is  determined  by  the 
method  adopted  by  the  Association  of  Official  Agricultural 
Chemists  which  is  as  follows:  "Evaporate  the  filtrate 
from  the  above  determination  on  water  bath  to  dryness 
and  carefully  heat  to  expel  ammonium  salts.  Take  up 
the  residue,  with  20  to  25  cc.  hot  water  and  about  5  cc. 
hydrochloric  acid,  filter,  and  wash.  Concentrate  to  about 
50  cc.,  cool,  and  add  sufficient  acid  sodium  phosphate  to 
precipitate  the  magnesium;  then  add  gradually  am- 
monium hydroxide,  with  constant  stirring,  until  the 
solution  is  distinctly  alkaline.  Test  with  acid-sodium- 
phosphate  to  be  sure  that  sufficient  has  been  added.  Al- 
low to  stand  one-half  hour,  then  add  gradually  10  cc.  of 
strong  ammonium  hydroxide,  cover  closely  to  prevent 
escape  of  ammonia,  and  let  stand  in  the  cold.  Filter 
after  12  hours,  wash  the  precipitate  free  from  chlorides, 
using  2.5  per  cent  ammonia  water,  dry,  burn  at  first  at 
moderate  heat,  then  ignite  intensely,  and  weigh  as  mag- 
nesium-pyro-phosphate  (Mg2P2O7)."  If  this  precipita- 
tion is  done  from  a  hot  solution  there  is  less  danger  of 
tertiary  magnesium  phosphate  being  formed.  Colori- 
metric  and  titration  methods  are  used  occasionally. 

Sodium.  —  Sodium  determinations  are  seldom  made  in 


94          METHODS  OF  DETERMINING  ALKALI 

alkali  studies  because  the  process  is  long  and  because  the 
quantity  present  can  be  roughly  estimated  by  elimination 
when  the  other  easier  determinations  have  been  made. 

Other  Methods  of  Determining  Soluble  Salts.  —  The 
Electric  Bridge.  —  A  modification  of  the  Wheatstone 
bridge  has  been  found  of  considerable  value  in  de- 
termining the  total  salts  in  either  soil  or  water  in  the 
field  without  chemical  analysis.  The  theory  upon  which 
the  instrument  works  is  based  upon  the  fact  that  the  re- 
sistance of  the  solution  varies  with  the  concentration  of 
its  soluble  salts.  It  has  been  found  of  great  value  for  de- 
termining the  total  salts  in  soils  which  do  not  contain  ex- 
cessive quantities  of  organic  matter,  and  especially  where 
the  salts  are  mostly  sodium  chloride  and  sodium  sulphate. 
It  becomes  unreliable  where  the  organic  matter  is  high 
and  it  is  necessary  to  determine  the  sodium  carbonate 
separately  from  the  other  salts  because,  the  resistance  is 
considerably  different. 

In  using  the  instrument,  the  soil  in  the  cup  is  first 
moistened  until  it  becomes  saturated  or  puddled  and  free 
from  air,  and  if  the  soil  is  very  dry  it  should  be  allowed  to 
stand  in  this  condition  for  about  20  minutes.  The  cup, 
which  is  just  levelful  of  the  saturated  soil,  is  placed  be- 
tween the  clips  through  which  the  current  passes,  and 
the  pointer  is  moved  back  and  forth  until  the  neutral  point 
is  reached  where  the  buzzing  in  the  receiver  is  at  a  mini- 
mum. The  instrument  has  coils  with  10,  100,  and  1000 
ohms  resistance,  and  it  is  necessary  to  adjust  the  coils 
until  the  proper  resistance  is  found.  "The  resistance  of 
the  cup  contents  is  found  by  multiplying  the  resistance 
of  the  comparison  coil  used,  shown  on  the  rotary  switch, 
by  the  number  on  the  scale  opposite  the  pointer,  when 
a  balance  is  established.  Thus,  if  the  comparison  coil 


DETERMINING  SOLUBLE   SALTS  95 

is  100  and  the  scale  reading  0.92,  the  resistance  of  the  cup 
is  92  ohms.  When  the  extra  loo-ohm  coil  is  used  with  the 
cup,  the  100  ohms  added  must  be  subtracted  from  the 
resistance  read  on  the  scale.  Thus  if  the  100  ohms  is  in 
series  with  the  cup  and  the  scale  reads  1.2,  while  the 
comparison  coil  shows  100  ohms,  then  the  resistance  of  the 
cup  and  coil  is  120  ohms.  Subtracting  the  100  ohms  of 
the  coil  leaves  20  ohms  as  the  resistance  due  to  the  cup. 
The  resistance  of  the  cup  contents  must  be  corrected  to  a 
temperature  of  60°  F.  To  do  this,  immediately  after 
reading  the  resistance,  a  thermometer  is  stuck  into  the  cup 
and  read  after  two  minutes.  The  resistance  at  the  tem- 
perature found  is  then  corrected  to  60°  F.  (by  means  of 
Table  XII).  Having  found  the  resistance  of  the  cup 
contents,  the  percentage  of  salt  may  be  determined  for 
soils  by  use  of  Table  XIII,  and  for  soil  solutions  by 
Table  XIV."  In  making  temperature  corrections,  which 
must  be  done -before  determining  the  parts  per  million  of 
salts  present,  the  column  containing  the  temperature  of 
the  soil  is  found.  The  sum  of  the  resistances  of  the  sep- 
arate digits  corresponding  to  the  resistance  at  the  given 
temperature  of  the  soil  is  found  and  the  sum  of  the  resist- 
ances of  the  separate  digits  corresponding  to  the  resistance 
at  the  given  temperatures  is  added.  "As  an  example  of 
its  use,  suppose  the  resistance  to  be  1349  ohms  at  72°  F. 
On  the  left-hand  side  of  the  table  find  72°  F.,  then  opposite 
under  the  columns  marked  '1000'  will  be  found  1170  ohms 
at  60°  F.  as  the  value  of  1000  at  72°  F. ;  3000  ohms  at  72°  F. 
will  be  found  equal  to  3510  at  60°  F.;  hence  300  is  equal 
to  351  at  60°  F.,  40  is  equal  to  46.8  ohms  at  60°  F.,  and  9  is 
equal  to  10.5  ohms  at  60°  F.,"  and  the  sum  of  these  re- 
sistances at  60°  F.  is  equal  to  1578.3  ohms,  which  is  the 
desired  resistance. 


96 


METHODS  OF   DETERMINING  ALKALI 


TABLE  XII.     REDUCTION  OF  THE  ELECTRICAL  RESISTANCE  OF 
SOILS  TO  A  UNIFORM  TEMPERATURE  OF  60°  F. 


°F. 

1OOO 

2000 

3000 

4000 

5000 

6000 

7OOO 

8000 

gooo 

32.0 

625 

,250 

,875 

2,500 

3,125 

3,750 

4,375 

5,000 

5,625 

32.5 

632 

,265 

,897 

2,530 

3,163 

3,795 

4,425 

5,059 

5,691 

33-o 

640 

,280 

,920 

2,560 

3,200 

3,840 

4,480 

5,120 

5,760 

33-5 

647 

,294 

,94i 

2,588 

3,235 

3,883 

4,530 

5,177 

5,824 

34-o 

653 

,306 

,959 

2,612 

3,265 

3,9i8 

4,57i 

5,224 

5,877 

34-5 

660 

,320 

1,980 

2,640 

3,300 

3,96o 

4,620 

5,280 

5,940 

35-o 

668 

,336 

2,004 

2,672 

3,340 

4,008 

4,676 

5,344 

6,OI2 

35-5 

675 

,350 

2,025 

2,700 

3,375 

4,050 

4,725 

5,4oo 

6,075 

36.0 

683 

,366 

2,049 

2,732 

3,4i5 

4,098 

4,781 

5,464 

6,147 

36.5 

690 

,380 

2,070 

2,760 

3,450 

4,140 

4,830 

5,520 

6,210 

37-o 

698 

,396 

2,094 

2,792 

3,490 

4,188 

4,886 

5,584 

6,282 

37-5 

704 

,408 

2,112 

2,816 

3,520 

4,224 

4,928 

5,632 

6,336 

38.0 

711 

,422 

2,133 

2,844 

3,555 

4,266 

4,977 

5,688 

6,399 

38.5 

717 

,434 

2,151 

2,868 

3,585 

4,302 

5,°T9 

5,736 

6,453 

39-o 

723 

,446 

2,169 

2,892 

3,6i5 

4,338 

5,061 

5,784 

6,507 

39-5 

729 

,458 

2,187 

2,916 

3,645 

4,374 

5,103 

5,832 

6,561 

40.0 

735 

,470 

2,205 

2,940 

3,675 

4,410 

5,i45 

5,880 

6,615 

40-5 

742 

,484 

2,226 

2,968 

3,7io 

4,452 

5,!94 

5,936 

6,678 

41.0 

750 

,50° 

2,250 

3,000 

3,750 

4,5oo 

5,250 

6,000 

6,750 

41-5 

757 

,514 

2,271 

3,028 

3,785 

4,542 

5,299 

6,056 

6,813 

42.0 

763 

,526 

2,289 

3,052 

3,8iS 

4,578 

5,34i 

6,104 

6,867 

42.5 

770 

,540 

2,310 

3,080 

3,850 

4,620 

5,390 

6,160 

6,930 

43-o 

776 

,552 

2,328 

3,I04 

3,880 

4,656 

5,432 

6,208 

6,984 

43-5 

782 

,564 

2,346 

3,128 

3,910 

4,692 

5,474 

6,256 

7,038 

44.0 

788 

,576 

2,364 

3,152 

3,940 

4,728 

5,5i6 

6,304 

7,092 

44-5 

794 

,588 

2,382 

3,!76 

3,970 

4,764 

5,558 

6,352 

7,146 

45-° 

800 

,600 

2,400 

3,200 

4,000 

4,800 

5,600 

6,400 

7,200 

45-5 

807 

,614 

2,421 

3,228 

4,035 

4,842 

5,649 

6,456 

7,263 

46.0 

814 

,628 

2,442 

3,256 

4,070 

4,884 

5,698 

6,512 

7,326 

46.5 

821 

,642 

2,463 

3,284 

4,io5 

4,926 

5,747 

6,568 

7,389 

47.0 

828 

,656 

2,484 

3,3i2 

4,140 

4,968 

5,796 

6,624 

7,452 

47-5 

835 

,670 

2,5°5 

3,340 

4,i75 

5,010 

5,845 

6,680 

7,5i5 

48.0 

843 

,686 

2,529 

3,372 

4,2i5 

5,058 

5,90i 

6,744 

7,587 

48.5 

850 

,700 

2,55o 

3,4oo 

4,250 

5,100 

5,950 

6,800 

7,650 

49-o 

856 

,712 

2,568 

3,424 

4,280 

5,i36 

5,992 

6,848 

7,704 

49-5 

862 

,724 

2,586 

3,448 

4,3io 

5,i72 

6,034 

6,896 

7,758 

50.0 

867 

,734 

2,601 

3,468 

4,335 

5,202 

6,069 

6,936 

7,803 

SO-S 

874 

,748 

2,622 

3,496 

4,370 

5,244 

6,118 

6,992 

7,866 

51.0 

881 

,762 

2,643 

3,524 

4,405 

5,286 

6,167 

7,048 

7,929 

5i-5 

887 

,774 

2,661 

3,548 

4,435 

5,322 

6,209 

7,096 

7,983 

52.0 

893 

,786 

2,679 

3,572 

4,465 

5,358 

6,251 

7,i44 

8,037 

52.5 

900 

,800 

2,700 

3,600 

4,5oo 

5,400 

6,300 

7,200 

8,100 

53-o 

906 

,812 

2,718 

3,624 

4,530 

5,436 

6,342 

7,248 

8,154 

53-5 

912 

,824 

2,736 

3,648 

4,56o 

5,472 

6,384 

7,296 

8,208 

54-0 

917 

,834 

2,75i 

3,668 

4,585 

5,502 

6,419 

7,336 

8,253 

DETERMINING   SOLUBLE   SALTS 
TABLE  XII.     (Concluded.) 


97 


°F. 

1000 

2000 

3000 

4000 

5000 

6000 

6000 

8000 

9000 

54-5 

925 

1,850 

2,775 

3,700 

4,625 

5,550 

6,475 

7,400 

8,325 

55-o 

933 

1,866 

2,799 

3,732 

4,665 

5,598 

6,53i 

7,464 

8,397 

55-5 

940 

1,880 

2,820 

3,76o 

4,700 

5,640 

,  6,580 

7,520 

8,460 

56.0 

947 

1,894 

2,841 

3,78o 

4,735 

5,682 

6,629 

7,576 

8,523 

56.5 

954 

1,908 

2,862 

3,816 

4,770 

5,724 

6,678 

7,632 

8,586 

57-0 

961 

1,922 

2,883 

3,844 

4,805 

5,766 

6,727 

7,688 

8,649 

57-5 

968 

i,936 

2,904 

3,872 

4,839 

5,807 

6,775 

7,743 

8,711 

58.0 

974 

1,948 

2,922 

3,896 

4,870 

5,844 

6,818 

7,792 

8,766 

58.5 

981 

1,961 

2,942 

3,923 

4,903 

5,884 

6,864 

7,845 

8,826 

59-0 

987 

i,974 

2,962 

3,949 

4,936 

5,923 

6,910 

7,898 

8,885 

59-5 

994 

1,988 

2,982 

3,976 

4,97i 

5,965 

6,959 

7,953 

8,947 

60.0 

,000 

2,000 

3,ooo 

4,000 

5,000 

6,000 

7,000 

8,oco 

9,000 

60.5 

,006 

2,013 

3,oi9 

4,026 

5,032 

6,039 

7,045 

8,052 

9,059 

61.0 

,013 

2,026 

3,039 

4,052 

5,065 

6,078 

7,091 

8,104 

9,H7 

61.5 

,020 

2,040 

3,060 

4,080 

5,100 

6,120 

7,140 

8,  1  60 

9,180 

62.0 

,027 

2,054 

3,081 

4,108 

5,135 

6,162 

7,189 

8,216 

9,243 

62.5 

,033 

2,067 

3,100 

4,i34 

5,167 

6,201 

7,234 

8,268 

9,302 

63.0 

,040 

2,080 

3,120 

4,160 

5,200 

6,240 

7,280 

8,320 

9,36o 

63.5 

,047 

2,094 

3,J4i 

4,188 

5,235 

6,282 

7,329 

8,376 

9,423 

64.0 

,054 

2,108 

3,162 

4,216 

5,270 

6,324 

7,378 

8,432 

9,486 

64-5 

,060 

2,121 

3,i8i 

4,242 

5,302 

6,363 

7,423 

8,484 

9,545 

65.0 

,067 

2,134 

3,201 

4,268 

5,335 

6,402 

7,469 

8,536 

9,603 

65.5 

,074 

2,148 

3,222 

4,296 

5,370 

6,444 

7,5i8 

8,592 

9,666 

66.0 

,081 

2,l62 

3,243 

4,324 

5,405 

6,486 

7,567 

8,648 

9,729 

66.5 

,088 

2,176 

3,264 

4,352 

5,440 

6,528 

7,616 

8,704 

9,792 

67.0 

,095 

2,I9O 

3,285 

4,38o 

5,475 

6,570 

7,665 

8,760 

9,855 

67-5 

,102 

2,205 

3,307 

4,410 

5,5i2 

6,615 

7,717 

8,820 

9,922 

68.0 

,110 

2,220 

3,330 

4,440 

5,550 

6,660 

7,770 

8,880 

9,990 

68.5 

,U7 

2,235 

3,352 

4,470 

5,587 

6,705 

7,823 

8,940 

10,058 

69.0 

,125 

2,250 

3,375 

4,5oo 

5,625 

6,750 

7,875 

9,000 

10,125 

69.5 

,133 

2,265 

3,398 

4,530 

5,663 

6,795 

7,928 

9,060 

10,193 

70.0 

,140 

2,280 

3,420 

4,56o 

5,7oo 

6,840 

7,980 

9,120 

10,260 

70-5 

,H7 

2,285 

3,442 

4,590 

5,737 

6,885 

8,032 

9,180 

10,327 

71.0 

,155 

2,310 

3,465 

4,620 

5,775 

6,930 

8,085 

9,240 

10,395 

71-5 

,162 

2,325 

3,487 

4,650 

5,812 

6,975 

8,i37 

9,300 

10,462 

72.0 

,170 

2,340 

3,5io 

4,680 

5,850 

7,020 

8,190 

9,36o 

io,530 

72.5 

,177 

2,355 

3,532 

4,710 

5,887 

7,065 

8,242 

9,420 

io,597 

73-o 

,185. 

2,370 

3,555 

4,740 

5,925 

7,  no 

8,295 

9,480 

10,665 

73-5 

,193 

2,386 

3,579 

4,772 

5,965 

7,i58 

8,35i 

9,544 

io,737 

74.0 

,201 

2,402 

3,603 

4,804 

6,005 

7,206 

8,407 

9,608 

10,809 

74-5 

,208 

2,416 

3,624 

4,832 

6,040 

7,248 

8,456 

9,664 

10.872 

75-o 

,215 

2,430 

3,645 

4,860 

6,075 

7,290 

8,505 

9,720 

io,935 

75-5 

1,222 

2,445 

3,667 

4,890 

6,112 

7,335 

8,557 

9,78o 

11,002 

76.0 

1,230 

2,460 

3,690 

4,920 

6,150 

7,38o 

8,610 

9,840 

11,076 

76-5 

1,237  ' 

2,475 

3,7i2 

4,950 

6,187 

7,425 

8,662 

9,900 

n,i37 

98          METHODS  OF   DETERMINING   ALKALI 
TABLE  XII.     (Continued.} 


°F. 

1000 

20OO 

3000 

4000 

5000 

6000 

7000 

8000 

9000 

77.0 

,245 

2,490 

3,735 

4,980 

6,225 

7,470 

8,7i5 

9,96o 

11,205 

77-5 

,253 

2,506 

3,759 

5,°12 

6,265 

7,5i8 

8,77i 

10,024 

11,277 

78.0 

,261 

2,522 

3,783 

5,044 

6,305 

7,566 

8,827 

10,088 

n,349 

78.5 

,269 

2,538 

3,807 

5,076 

6,345 

7,614 

8,883 

10,152 

11,421 

79.0 

,277 

2,554 

3,83i 

5,108 

6,385 

7,662 

8,939 

10,216 

n,493 

79-5 

,285 

2,576 

3,856 

5,H2 

6,427 

7,713 

8,998 

10,284 

11,569 

80.0 

,294 

2,598 

3,882 

5,i76 

6,470 

7,764 

9,058 

10,352 

1  1  ,646 

80.5 

,302 

2,609 

3,9o6 

5,208 

6,510 

7,812 

9,H4 

10,416 

11,718 

81.0 

,310 

2,620 

3,930 

5,240 

6,550 

7,860 

9,170 

10,480 

11,790 

81.5 

,318 

2,637 

3,955 

5,274 

6,592 

7,9H 

9,229 

10,546 

11,866 

82.0 

,327 

2,654 

3,98i 

5,3o8 

6,635 

7,962 

9,289 

10,616 

n,943 

82.5 

,335 

2,670 

4,005 

5,340 

6,675 

8,010 

9,345 

10,680 

12,015 

83.0 

,343 

2,686 

4,029 

5,372 

6,7i5 

8,058 

9,401 

10,744 

12,087 

83-5 

,35i 

2,702 

4,053 

5,404 

6,755 

8,106 

9,457 

10,808 

12,159 

84.0 

,359 

2,718 

4,077 

5,436 

6,795 

8,154 

9,513 

10,872 

12,231 

84-5 

,367 

2,735 

4,102 

5,470 

6,837 

8,205 

9,572 

10,940 

12,307 

85.0 

,376 

2,752 

4,128 

5,504 

6,830 

8,256 

9,632 

1  1,  008 

12,384 

85-5 

,385 

2,769 

4,153 

5,538 

6,922 

8,307 

9,691 

11,076 

12,460 

86.0 

,393 

2,786 

4,179 

5,572 

6,965 

8,358 

9,75i 

11,144 

12,537 

86.5 

,401 

2,802 

4,203 

5,604 

7,005 

8,406 

9,807 

11,208 

12,609 

87.0 

,409 

2,818 

4,227 

5,636 

7,045 

8,454 

9,863 

11,272 

12,681 

87.5 

,418 

2,836 

4,254 

5,672 

7,090 

8,508 

9,93i 

n,344 

12,762 

88.0 

,427 

2,854 

4,281 

5,7o8 

7,135 

8,562 

9,989 

11,416 

12,843 

88.5 

,435 

2,870 

4,305 

5,740 

7,i75 

8,610 

10,040 

11,480 

12,915 

89.0 

,443 

2,886 

4,329 

5,772 

7,215 

8,658 

10,091 

n,544 

12,987 

89.5 

,4Si 

2,903 

4,354 

5,800 

7,257 

8,709 

10,155 

1  1,  612 

13,063 

90.0 

,460 

2,920 

4,38o 

5,840 

7,300 

8,760 

10,220 

i  i,  680 

13,140 

QO-S 

,468 

2,937 

4,405 

5,874 

7,342 

8,8n 

10,279 

11,748 

13,216 

91.0 

,477 

2,954 

4,43i 

5,908 

7,385 

8,862 

10,339 

11,816 

13,293 

9i-5 

,486 

2,972 

4,458 

5,944 

7,430 

8,916 

10,402 

11,888 

13,374 

92.0 

,495 

2,990 

4,485 

5,98o 

7,475 

8,970 

10,465 

11,960 

13,455 

92-5 

,504 

3,oo8 

4,512 

6,016 

7,520 

9,024 

10,528 

12,032 

13,536 

93-0 

,5i3 

3,026 

4,539 

6,052 

7,565 

9,078 

10,591 

12,104 

13,617 

93-5 

,522 

3,035 

4,567 

6,090 

7,612 

9,i35 

10,657 

12,180 

13,7    2 

94.0 

,532 

3,064 

4,596 

6,128 

7,660 

9,192 

10,724 

12,256 

13,788 

94-5 

,54i 

3,083 

4,624 

6,  1  66 

7,707 

9,249 

10,790 

12,332 

13,873 

9S-o 

,55i 

3,102 

4,653 

6,204 

7,755 

9,3o6 

10,857 

12,408 

13,959 

95-5 

,56o 

3,121 

4,681 

6,242 

7,802 

9,363 

10,923 

12,484 

14,040 

96.0 

,570 

3,140 

4,7io 

6,280 

7,850 

9,420 

10,990 

12,560 

14,130 

96.5 

,58o 

3,160 

4,740 

6,320 

7,900 

9,480 

1  1,  060 

12,640 

14,220 

97-9 

,590 

3,180 

4,770 

6,360 

7,950 

9,540 

11,130 

12,720 

14,310 

97-5 

,600 

3,201 

4,801 

6,402 

8,002 

9,603 

11,203 

12,804 

14,404 

98.0 

,611 

3,222 

4,833 

6,444 

8,055 

9,666 

11,277 

12,888 

14,499 

•98.5 

,620 

3,240 

4,860 

6,480 

8,100 

9,720 

n,34o 

12,960 

14,580 

99.0 

,629 

3,258 

4,887 

6,516 

8,i45 

9,774 

11,403 

13,032 

I4,66l 

DETERMINING  SOLUBLE   SALTS 


99 


TABLE  XIII.    SOLUBLE  SALTS  IN  SOIL  SOLUTIONS  OF  VARIOUS  RESISTANCES 
AT  60°  F. 


R.at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.at 

60° 
F. 

Parts 
per 
mil- 
lion 

R.at 

60° 
F. 

Parts 
per 
mil- 
lion 

68 

3500 

118 

869 

1  68 

268 

218 

945 

268 

731 

*3i8 

620 

366 

549 

6g 

400 

119 

851 

169 

260 

219 

940 

269 

728 

319 

618 

366.5 

548 

70 

300 

1  20 

834 

170 

252 

220 

935 

270 

725 

320 

616 

367 

547 

71 

250 

121 

817 

171 

244 

221 

930 

271 

722 

321 

614 

367-5 

546 

72 

200 

122 

800 

172 

236 

222 

925 

272 

7ig 

322 

612 

368 

545 

73 

ISO 

123 

783 

173 

228 

223 

g2o 

273 

716 

323 

610 

368.5 

544 

74 

IOO 

124 

766 

174 

220 

224 

915 

274 

713 

324 

608 

369 

543 

75 

50 

125 

749 

175 

212 

225 

gio 

275 

710 

325 

606 

369.5 

542 

76 

3000 

126 

732 

176 

205 

226 

905 

276 

707 

326 

604 

370 

541 

77 

2950 

127 

715 

177 

I98 

227 

goo 

277 

704 

327 

602 

370.5 

540 

78 

goo 

128 

1700 

178 

igi 

228 

8gs 

278 

701 

328 

600 

371 

539 

79 

850 

i2g 

685 

179 

184 

229 

8go 

279 

6g8 

329 

598 

371-5 

538 

80 

800 

130 

670 

1  80 

177 

230 

885 

280 

6g6 

330 

596 

372 

537 

81 

767 

131 

655 

181 

170 

231 

880 

281 

6g4 

331 

594 

372-5 

536 

82 

733 

132 

640 

182 

163 

232 

875 

282 

692 

332 

592 

373 

535 

83 

700 

133 

626 

183 

156 

233 

870 

283 

6go 

333 

590 

373-5 

534 

84 

667 

134 

613 

184 

149 

234 

865 

284 

688 

334 

588 

374 

533 

8$ 

633 

135 

600 

185 

142 

235 

860 

285 

686 

335 

586 

374-5 

532 

86 

600 

136 

587 

186 

236 

855 

286 

684 

336 

584 

375 

531 

87 

57i 

137 

574 

187 

128 

237 

850 

287 

682 

337 

582 

375-5 

530 

88 

542 

138 

562 

188 

II2I 

238 

845 

288 

680 

338 

5°o 

376 

529 

89 

513 

139 

550 

189 

III4 

239 

840 

28g 

678 

339 

578 

376.5 

528 

go 

484 

140 

538 

i  go 

107 

240 

835 

290 

676 

340 

577 

377 

527 

gi 

456 

141 

527 

igi 

IOO 

241 

830 

291 

674 

341 

576 

377-5 

526 

92 

427 

142 

ig2 

93 

242 

825 

292 

672 

342 

575 

378 

525 

93 

400 

143 

505 

193 

86 

243 

820 

293 

670 

343 

574 

378.5 

524 

94 

375 

144 

494 

194 

80 

244 

815 

294 

668 

344 

573 

379 

523 

3 

350 
325 

^46 

483 
472 

ig6 

74 
68 

245 
246 

810 

805 

295 
296 

666 
664 

345 
346 

572 
571 

379-5 
380 

522 
521 

97 

300 

147 

461 

197 

62 

247 

800 

297 

662 

347 

570 

380.5 

520 

98 

276 

148 

450 

198 

56 

248 

796 

298 

660 

348 

569 

38i 

519 

99 

253 

149 

440 

igg 

So 

249 

792 

2gg 

658 

349 

568 

381.5 

5i8 

IOO 

230 

150 

430 

200 

44 

250 

788 

300 

656 

350 

567 

382 

5^7 

101 

208 

151 

420 

2OI 

38 

251 

784 

301 

654 

351 

566 

382.5 

516 

IO2 

186 

152 

410 

202 

32 

252 

780 

302 

652 

352 

565 

383 

515 

103 

164 

153 

400 

203 

26 

253 

776 

303 

650 

353 

S64 

383-5 

514 

104 

142 

154 

390 

204 

20 

254 

773 

304 

648 

354 

563 

384 

513 

105 

121 

155 

38o 

205 

14 

255 

770 

305 

646 

355 

562 

384-5 

512 

106 

IOO 

156 

370 

206 

8 

256 

767 

306 

644 

356 

56i 

385 

5" 

107 

79 

157 

36o 

207 

2 

257 

764 

307 

642 

357 

560 

386 

108 

59 

158 

350 

208 

996 

258 

761 

308 

640 

358 

559 

386.5 

509 

log 

39 

341 

209 

ggo 

259 

758 

3og 

638 

359 

558 

387 

508 

no 

go 

1  60 

332 

210 

985 

260 

755 

310 

636 

360 

557 

387-5 

507 

in 

2000 

161 

324 

211 

g8o 

261 

752 

3" 

634 

361 

556 

388 

506 

112 

ig8i 

162 

212 

975 

262 

749 

312 

632 

362 

555 

389 

505 

"3 

g62 

163 

308 

213 

970 

263 

746 

3i3 

630 

363 

554 

sgo 

504 

114 

943 

164 

300 

214 

g6s 

264 

743 

314 

628 

364 

553 

390.  5 

503 

"5 

924 

165 

292 

215 

g6o 

265 

740 

626 

364.5 

552 

39i 

502 

116 

90S 

166 

284 

2x6 

gss 

266 

737 

in 

624 

365 

551 

391-5 

501 

117 

887 

167 

276 

217 

950 

267 

734 

317 

622 

365.5 

550 

392 

500 

100        METHODS  OF  DETERMINING  ALKALI 


TABLE  XIII.     (Continued.) 


R.at 

60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 

60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 

60° 

F. 

Parts 
per 
mil- 
lion 

3Q2-S 

499 

433-8 

449 

483-2 

399 

549-5 

349 

636 

299 

754 

249 

924 

199 

393 

498 

434-6 

448 

484-4 

398 

55i 

348 

638 

298 

757 

248 

928 

198 

393-5 

497 

435-4 

447 

485-6 

397 

552-5 

347 

640 

297 

760 

247 

932 

197 

394 

496 

436.2 

446 

486.8 

396 

554 

346 

642 

296 

762 

246 

936 

196 

394-5 

495 

437 

4  5 

488 

395 

555-5 

345 

644 

295 

765 

245 

940 

195 

395 

494 

438.0 

444 

489.2 

394 

557 

344 

646 

294 

768 

244 

944 

194 

396 

493 

439-0 

443 

490.4 

393 

558.5 

343 

648 

293 

771 

243 

948 

193 

397 

492 

440.0 

442 

491.6 

392 

56o 

342 

650 

292 

774 

242 

953 

192 

398 

491 

441.0 

441 

492.8 

391 

561.5 

341 

652 

291 

777 

241 

958 

191 

399 

490 

442 

440 

494 

390 

563 

340 

654 

290 

780 

240 

962 

190 

400 

489 

442-8 

439 

495 

389 

565 

339 

656 

289 

783 

239 

966 

189 

400.8 

488 

443-6 

438 

496 

388 

567 

338 

658 

288 

786 

238 

971 

1  88 

401.6 
402.4 

487 
486 

444-4 
445-2 

437 
436 

497-5 
499 

387 
386 

568.5 
570 

337 
336 

661.5 
663 

287 
286 

789 
792 

237 
236 

976 
981 

187 
186 

403 

485 

446 

435 

500.5 

385 

571-5 

335 

665 

285 

795 

235 

985 

185 

403-8 

484 

447 

434 

502 

384 

573 

334 

667 

284 

798 

234 

990 

184 

404.6 

483 

448 

433 

503 

383 

574-5 

333 

669.5 

283 

801 

233 

995 

183 

405-4 

482 

449 

432 

504 

382 

576 

332 

672 

282 

804 

232 

IOOO 

182 

406.  2 

481 

450 

431 

505-5 

38r 

578 

331 

674 

281 

807 

231 

1005 

181 

407 

480 

4SI 

430 

507 

380 

58o 

330 

676 

280 

811 

230 

IOIO 

180 

407-8 

479 

452 

429 

508 

379 

581-5 

329 

678.5 

279 

814 

229 

1016 

179 

408.6 

478 

453 

428 

509 

378 

583 

328 

681 

278 

817 

228 

IO22 

178 

409-4 

477 

454 

427 

510.5 

377 

584-5 

327 

683 

277 

820 

227 

IO27 

177 

410.2 
411 

476 

475 

455 
456 

426 

425 

512 
513 

376 
375 

586 
587.5 

326 
325 

685 
687.5 

276 
275 

824 
827 

226 
225 

IO32 
1038 

176 

175 

4II.8 

474 

457 

424 

514 

374 

589 

324 

690 

274 

830 

224 

1044 

174 

412.6 

473 

458 

423 

515.5 

373 

59i 

323 

692.5 

273 

834 

223 

1049 

173 

413-4 

472 

459 

422 

517 

372 

593 

322 

695 

272 

837 

222 

1055 

172 

414.2 

471 

460 

421 

518.5 

371 

594-5 

321 

697-5 

271 

841 

221 

1060 

171 

415 

470 

461 

420 

520 

370 

596 

320 

700 

270 

844 

22O 

1067 

170 

415-8 

469 

462 

419 

521 

369 

598 

319 

702 

269 

848 

219 

1073 

169 

4l6.6 

468 

463 

418 

522 

368 

600 

318 

704 

268 

851 

218 

1079 

1  68 

417.4 

497 

464 

417 

523-5 

367 

601.5 

317 

707 

276 

854 

217 

1085 

167 

418.2 

466 

465 

416 

525 

366 

603 

316 

709 

266 

858 

216 

1091 

1  66 

419 

465 

466 

VS 

526 

365 

605 

315 

712 

265 

862 

215 

1097 

165 

420 

464 

467 

414 

527 

364 

607 

314 

715 

264 

865 

214 

1104 

\64 

421.0 

463 

468 

413 

528.5 

363 

609 

313 

717 

263 

869 

213 

I  IIO 

163 

422.0 

462 

469 

412 

530 

362 

611 

312 

720 

262 

872 

212 

1118 

162 

423-D 

461 

470 

411 

531-5 

361 

612.5 

311 

722 

261 

876 

211 

1125 

161 

424 

460 

471 

410 

533 

360 

614 

3io 

725 

260 

880 

2IO 

1132 

1  60 

424.8 

459 

472.2 

409 

534-5 

359 

616 

309 

727 

259 

884 

209 

1140 

159 

425-6 

458 

473-4 

408 

536 

358 

618 

308 

730 

258 

887 

208 

1147 

158 

426.4 

457 

474.6 

407 

537-5 

357 

620 

307 

732 

257 

891 

207 

"54 

157 

427.2 

456 

475-8 

406 

539 

356 

622 

306 

735 

256 

895 

206 

1161 

156 

428.0 

455 

477 

405 

540-5 

355 

624 

305 

738 

255 

899 

205 

1168 

155 

42Q.O 

454 

478 

404 

542 

354 

626 

304 

740 

254 

903 

204 

1176 

154 

430.0 

453 

479 

403 

543-5 

353 

628 

303 

743 

253 

907 

203 

1184 

153 

431-0 

452 

480 

402 

545 

352 

630 

302 

746 

252 

911 

2O2 

1192 

152 

432.0 

451 

48l 

401 

546-5 

35i 

632 

301 

749 

251 

9iS 

201 

1200 

151 

433 

450 

482 

400 

548 

350 

634 

300 

751 

250 

920 

200 

1208 

ISO 

DETERMINING  SOLUBLE   SALTS 

TABLE  XIII.     (Continued.) 


R.at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.  at 
60° 
F. 

Parts 
per 
mil- 
lion 

R.at 

60° 
F. 

Parts 
per 
mil- 
lion 

R.at 

60° 
F. 

Parts 
per 
mil- 
lion 

R.at 
60° 
F. 

Parts 
per 
mil- 
lion 

1216 

149 

1394 

129 

1629 

109 

1972 

89 

2522 

69 

3450 

49 

534° 

29 

1224 

148 

1404 

128 

1645 

108 

1991 

88 

2555 

68 

35o8 

48 

SSoo 

28 

1232 

147 

1414 

127 

1661 

107 

201  1 

87 

2593 

67 

3576 

47 

5660 

27 

1240 

146 

1423 

126 

1678 

106 

2033 

86 

2631 

66 

3648 

46 

5820 

26 

1248 

US 

1433 

125 

1695 

105 

2055 

85 

2670 

65 

3717 

45 

6020 

25 

1257 

144 

1443 

124 

1712 

104 

2079 

84 

2712 

£4 

3288> 

44 

6260 

24 

1265 

143 

i4S3 

123 

1729 

103 

2103 

83 

2755 

63 

3858 

43 

6560 

23 

1274 

142 

1464 

122 

1746 

102 

2128 

82 

2798 

62 

3935 

42 

6980 

22 

1283 

141 

1475 

121 

1763 

101 

2152 

81 

2842 

61 

4005 

4i 

7240 

21 

1292 

140 

1486 

1  2O 

1780 

IOO 

2177 

80 

2886 

60 

4090 

40 

7600 

2O 

1301 

139 

1498 

119 

1797 

99 

2203 

79 

2932 

59 

4180 

39 

7900 

19 

1310 

138 

1509 

118 

1814 

98 

2232 

78 

2978 

58 

4275 

38 

8250 

18 

1320 

137 

1520 

117 

1831 

97 

2259 

77 

3025 

57 

4375 

37 

8800 

17 

1328 

136 

1533 

116 

1848 

96 

2288 

76 

3071 

56 

4475 

36 

9300 

16 

1337 

135 

1546 

us 

1865 

95 

2320 

75 

3120 

55 

4580 

35 

9700 

iS-5 

1346 

134 

1559 

114 

1882 

94 

2351 

74 

3170 

54 

4695 

34 

10087 

15 

1355 

133 

1572 

113 

1900 

93 

2383 

73 

3220 

53 

4810 

33 

IO2OO 

14.9 

1365 

132 

1585 

112 

1918 

92 

2416 

72 

3277 

52 

4925 

32 

1374 

131 

1599 

III 

1936 

91 

2451 

71 

3336 

Si 

5050 

31 

1384 

130 

1614 

no 

1954 

90 

2486 

70 

3394 

50 

5195 

30 

TABLE  XIV. 


PERCENTAGE  OF  MIXED  SALTS  IN  SOIL  TYPES  WITH 
A  GIVEN  RESISTANCE 


Resist- 
ance at 
60°  F. 

Sand 

Loam 

Clay 
loam 

Clay 

Resist- 
ance at 
60°  F. 

Sand 

Loam 

Clay 
loam 

Clay 

Ohms 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

Ohms 

Per  cent 

Per  cent 

Per  cent 

Per  cent 

18 

3-00 

3.00 

.... 

.... 

95 

•35 

•37 

•39 

.42 

19 

2.40 

2.64 

3.00 

IOO 

•33 

•35 

•37 

•39 

20 

2.  2O 

2.42 

2.80 

3.00 

105 

•3i 

•33 

•35 

•37 

25 

1.50 

1.70 

1.94 

2.  2O 

no 

•30 

•32 

•33 

•35 

30 

1.24 

i-34 

1.46 

1.58 

115 

.28 

.29 

•3i 

•33 

35 

1.04 

1.14 

I  .22 

1.32 

120 

.27 

.28 

.29 

•32 

40 

.86 

•94 

I  .04 

I.I4 

125 

•25 

.26 

.28 

•30 

45 

•75 

.78 

.88 

.98 

130 

.24 

•25 

.26 

.28 

5° 

.67 

•7i 

•77 

.86 

135 

•23 

.24 

•25 

.27 

55 

.60 

.64 

.69 

•77 

I4O 

.22 

•23 

.24 

.26 

60 

•55 

•58 

•63 

.70 

145 

.21 

.22 

•23 

•25 

65 

•5i 

•54 

•57 

•63 

150 

.  21 

.21 

.22 

.24 

70 

.48 

•50 

•53 

•59 

155 

.20 

.21 

.21 

•23 

75 

•45 

•47 

•50 

•55 

1  60 

.20 

.20 

.21 

.22 

80 

.42 

•44 

•47 

•5i 

165 

.19 

.  2O 

.20 

.21 

85 

•39 

.42 

•44 

.48 

170 

.19 

.19 

.  2O 

.20 

90 

•37 

•39 

.41 

•45 

102         METHODS  OF  DETERMINING  ALKALI 


In  using  the  bridge,  Beam  and  Freak  (2)  found  it  pos- 
sible to  eliminate  calcium  sulphate  from  the  total  salts 
by  using  40  per  cent  alcohol  in  extracting  the  salt  and 
comparing  the  resistance  with  that  found  for  this  solvent 
under  known  conditions.  By  determining  both  alcohol 
and  water  extraction  results,  the  difference  shows  the 
calcium  sulphate. 


FIG.  14.  —  DETERMINING  SOLUBLE  SALTS  WITH  THE  ELECTRIC 
BRIDGE  IN  THE  FIELD. 


Freezing-point  Method.  —  A  method  for  determining 
the  total  soluble  salts  in  soils  by  means  of  differences  in 
the  lowering  of  the  freezing  point  due  to  differences  in 
concentration  of  the  soil  solution,  has  been  worked  out  by 
Bouyoucos  and  McCool  (3).  About  an  inch  of  the  soil  is 
placed  in  an  isolated  tube  surrounded  by  salt-ice  water 
with  a  temperature  of  about  —  4.5°  C.  and  a  delicate 
Beckmen  thermometer  inserted  in  the  soil.  The  soil  is 
first  supercooled  to  about  i  degree  C.  below  its  freezing 
point  and  is  then  disturbed  so  that  the  temperature  rises 


REFERENCES  103 

until  it  remains  constant  for  some  time.  This  maximum 
temperature  is  recorded  as  the  freezing  point  of  the  soil. 
By  this  method,  as  by  the  electric  bridge,  the  quantity 
of  moisture  in  the  soil  plays  an  important  part  in  the 
concentration  of  the  solution,  hence  it  is  essential  that 
a  constant  quantity  of  water  be  present.  Fine  soils 
show  the  influence  of  changes  in  moisture  content  much 
more  than  do  sands  or  other  coarse  soils.  In  this  method, 
as  with  the  bridge,  the  determination  is  indirect  and  to 
get  the  total  salts  the  depression  of  the  freezing  point  must 
be  referred  to  the  depression  of  soils  under  similar  con- 
ditions with  known  quantities  of  salts.  The  limitations 
of  the  method  have  not  been  worked  out  as  yet,  but  much 
is  hoped  from  it. 

Biological  Method.  —  Another  indirect  method  being 
developed  by  biologists  is  based  on  the  effect  of  alkali  salts 
on  bacterial  action.  This  method  has  been  extensively 
used  by  Lipman,  Greaves,  and  Brown  and  their  co-workers 
and  depends  on  the  influence  of  soluble  salts  on  the  am- 
monifying, nitrifying,  and  nitrogen-fixing  organisms.  Sev- 
eral experimenters  have  noted  that  the  change  in  the 
quantity  of  salts  present  in  soils  affects  the  soil  flora 
somewhat  in  proportion,  but  to  what  extent  this  activity 
may  be  taken  as  an  indication  of  the  salts  present  is  yet 
to  be  seen. 

REFERENCES 

1.  BARNES,  J.  H.,  and  ALT,  BARKAT.     Alkali  Soils:    Some  Biochemical 

Factors  in  Their  Reclamation.     Agr.  Jour.  India,  12  (1917),  pp.  368- 
389.     (Abs.  E.  S.  R.  38,  p.  815.) 

2.  BEAM,  W.,  and  FREAK,  G.  A.     An  Improvement  in  the  Electrical 

Method  of  Determining  Salt  in  Soil.     Cairo  Sci.  Jour.  8  (1914), 
pp.  130-133-     (Abs.  E.  S.  R.  32,  p.  806.) 

3.  BOUYOUCOS,  G.  J.,  and  McCooL,  M.  M.    The  Freezing-point  Method 

as  a  Means  of  Measuring  the  Concentration  of  the  Soil  Solution 


104      METHODS    OF    DETERMINING   ALKALI 

Directly  in  the  Soil.     Mich.  Sta.  Tech.  Bui.  24  (1915),  44  pp.;  also 
Jour.  Agr.  Res.  15  (1918),  pp.  331-336. 

4.  CAMERON,  F.  K.     Estimation  of  Alkali  Carbonates  in  the  Presence  of 

Bicarbonates.     Am.  Chem.  Jour.  23  (1900),  pp.  471-486. 

5.  DAVIS,  R.  O.  E.,  and  BRYAN,  H.     The  Electrical  Bridge  for  the  De- 

termination of  Soluble  Salts  in  Soils.     U.  S.  D.  A.  Bur.  Soils  Bui.  61 
(1910),  36  pp. 

6.  GREAVES,  J.  E.,  and  HIRST,  C.  T.     Some  Factors  Influencing  the  Quan- 

titative Determination  of  Nitric  Nitrogen  in  the  Soil.     Soil  Sci.  4 
(1917),  pp.  179-203- 

7.  HARE,  R.  F.     A  Review  and  Discussion  of  Some  of  the  Methods  for 

the  Determination  of  Alkali  Soils.     N.  Mex.  Sta.  Bui.  95  (1915), 
pp.  7-16. 

8.  PITTMAN,  D.  W.    A  Study  of  Methods  of  Determining  Soil  Alkali. 

Utah  Sta.  Bui.  170  (1919),  21  pp. 

9.  SCHREINER,  O.,  and  FAILYER,   G.  H.     Colorimetric,  Turbidity,  and 

Titration  Methods  Used  in  Soil  Investigations.     U.  S.  D.  A.  Bur. 
Soils,  Bui.  31  (1906),  160  pp. 

10.  SKINNER,  W.  W.    A  Method  for  the  Determination  of  Black  Alkali 

in  Irrigating  Waters  and    Soil   Extracts.     Jour.  Am.  Chem.  Soc. 
28  (1906),  pp.  77-80. 

11.  STEWART,  R.,  and  GREAVES,  J.  E.    The  Influence  of  Chlorine  on  the 

Determination  of  Nitrates  by  the  Phenoldisulphonic  Acid  Method. 
Jour.  Am.  Chem.  Soc.  35  (1913),  pp.  579-582. 

12.  VINSON,  A.  E.,  and  CATLTN,  C.  N.     Study  of  Methods  Used  in  Alkali 

Determinations.     Ariz.  Sta.  24  Ann.  Rpt.  (1913),  pp.  274-277. 

13.  WILEY,  H.  W.     Official  and  Provisional  Methods  of  Analysis.     U.  S, 

D.  A.  Bur.  Chem.  Bui.  107  (Revised)  (1908),  pp.  272. 


CHAPTER  VIII 


CHEMICAL   EQUILIBRIUM   AND   ANTAGONISM 

THE  soil  is  not  static  but  is  in  a  state  of  constant  change. 
The  numerous  chemical  compounds  of  which  it  is  com- 
posed are  made  to  react  with  one  another  by  the  con- 
tinuous variation  in  such  factors  as  temperature,  moisture, 
decomposition  of  organic  matter,  the  growth  of  plant 
roots,  and  the  activities  of  microorganisms.  These 
agencies  of  change  make  it  practically  impossible  to  main- 
tain in  the  soil  for  any  length  of  time  a  stable  equilibrium. 
This  renders  an  understanding  of  the  alkali  problem  very 
difficult,  since  the  concentration  of  salts  in  any  particular 

TABLE  XV.    PARTS  or  SALTS  SOLUBLE  IN  100  PARTS  OF  WATER  l 
(Compiled  from  Handbook  of  Physics  and  Chemistry,  1919) 


Tem- 
per- 
ature 

Na,a 

Na2SO< 

CaCl2 

MgCh 

MgS04 

CaSO4 

NaCl 

NaNOa 

O° 

7-1 

5-0 

59-5 

q 

52.8 

26.0 

.179 

35-6 

73-0 

2O 
30 

21.4 
40.9 

o 

H 

19.4 
40.0 

§ 

74-5 

IOI  .0 

vO 

54-5 

35-6 
40.9 

§ 

.206 

35-8 
36.1 

88.0 

31-8 

46.0 

H 

q 

32-4 

q 

49-9 

35-i 

5I    0 

m 

50 
80 

47-5 
45-6 

§ 

46.8 

43-7 

I 
I 

132.0 
147.0 

§ 

66.0 

5°-4 
64.2 

O 
W 



36.7 
38.0 

114.0 
148.0 

100 

45-2 

42.7 

159.0 

73-o 

73-8 

.178 

39-i 

175-5 

1  The  figures  are  given  in  terms  of  the  anhydrous  salt,  but  the  solubili- 
ties quoted  are  for  those  hydrates  which  are  stable  at  the  stated  temperature. 

105 


106    CHEMICAL   EQUILIBRIUM   AND   ANTAGONISM 

zone  of  the  soil  is  not  always  the  same.  Salts  readily 
move  through  the  soil  and,  on  coming  in  contact  with  other 
salts,  chemical  changes  result.  The  toxicity  of  the  salts 
is  also  altered  by  the  presence  of  other  salts. 

Solubility  of  Alkali  Salts.  —  The  solubility  of  the  salts 
commonly  concerned  with  alkali  work  is  presented  in 
Table  XV. 

The  wide  difference  in  the  solubility  of  the  salts  and  the 
importance  of  temperature  is  brought  out  from  the  above 
figures.  It  will  be  noticed,  however,  that  the  quantity 
of  salts  which  may  dissolve  in  water  is  several  times  the 
quantity  ordinarily  found  in  extracts  of  soil  from  alkali 
lands. 

Mass  Action.  —  In  the  discussion  of  alkali  it  is  generally 
assumed  that  the  salts  are  stable  or  retain  the  same  com- 
position as  they  do  in  a  simple  solution.  This  stable  con- 
dition is  not  found,  however.  Analyses  of  different  depths 
of  alkali  soil,  for  instance,  have  indicated  an  apparent 
change,  under  certain  conditions,  of  part  of  the  harmful 
sodium  carbonate  into  the  much  less  toxic  sodium  bicar- 
bonate as  it  was  brought  close  to  the  surface  where  there 
was  more  carbonic  acid. 

In  order  that  a  clearer  understanding  of  the  conditions 
favoring  changes  in  the  nature  of  the  salts  in  the  soil 
may  be  had,  a  short  discussion  of  the  "Law  of  the  Mass 
Action"  seems  desirable.  This  law  states  that  the  amount 
of  chemical  action  is  proportional  to  the  active  mass,  or 
molecular  concentration  of  each  of  the  reacting  substances, 
in  unit  volume.  Quantitatively,  this  law  may  be  expressed 
in  its  most  general  form  as  follows: 

Assume  the  reaction 

nA+mB+  •  •  •  ^  pX  +  qY  +  -  -  - 


MASS  ACTION  107 

to  take  place  so  that  n  moles  of  A  are  capable  of  reacting 
with  m  moles  of  B  to  form  p  moles  of  X  and  q  moles  of  F, 
or  vice  versa  if  the  number  of  moles  of  A,  B,  .  .  .  X,  Y, 
.  actually  present  in  unit  volume  of  the  reacting  mixture 
are  represented  respectively  by  Ci,  C2,  .  .  .  di,  d>2,  .  .  ., 
and  further  if  sufficient  time  be  allowed  to  permit  the 
system  to  come  to  equilibrium,  then  at  a  given  temperature 
the  condition  of  the  system  is  expressed  by  the  equation 

di'df  ..... 

-  =  a  constant. 


This  relation  is  readily  understood  when  one  considers 
that  a  chemical  reaction  takes  place  as  a  result  of  very 
minute  particles  (molecular  or  ionic)  of  the  reacting  ma- 
terials coming  into  intimate  contact  with  each  other. 
Obviously  the  amount  of  chemical  action  will  depend  on 
the  number  of  these  particles  present  in  a  given  volume. 
Moreover,  if  one  of  these  materials  is  in  great  excess  in 
the  system,  it  would  be  expected  that  the  substance  with 
which  it  tended  to  react  would  at  equilibrium  be  nearly 
all  used  up. 

In  the  case  of  solutions  of  inorganic  salts,  the  reactions 
are  for  the  most  part  ionic  and  take  place  therefore  with 
great  rapidity.  It  also  frequently  happens  that  one  of 
the  reacting  bodies  is  only  slightly  soluble;  and  this  fact 
predisposes  the  reaction  in  favor  of  its  continued  forma- 
tion. But  as  no  salt  can  be  said  to  be  completely  insolu- 
ble, it  is  quite  possible  for  a  reaction  to  take  place,  having 
a  so-called  insoluble  substance  as  one  of  the  starting 
materials. 

For  example,  consider  the  reaction 

Na2C03  +  CaCl2  ±;  2  NaCl  +  CaC03 
which  normally  proceeds  from  left  to  right  on  account  of 


108    CHEMICAL   EQUILIBRIUM   AND   ANTAGONISM 

the   insolubility   of    calcium    carbonate.    The   mass   law 
states  that  at  a  given  temperature 

(NaCl)2(CaC03) 


(Na2C03)(CaCl2) 


=  a  constant, 


where  each  one  of  the  factors  of  the  equation  represents 
the  concentration  in  moles  of  that  constituent  in  unit 
volume.  Though  the  factor  (CaCOs)  is  very  small  it  is 
not  zero  and  accordingly  if  water  containing  a  large  amount 
of  sodium  chloride  were  passed  over  limestone  there  would 
be  a  tendency  for  calcium  carbonate  to  be  changed  into 
sodium  carbonate  and  calcium  chloride,  in  order  that  this 
equation  might  be  fulfilled. 

This  latter  condition  has  been  found  to  exist  in  certain 
parts  of  Egypt  where  the  soil  contained  excessive  quantities 
of  sodium  chloride  and  also  contained  calcium  carbonate. 
Instead  of  the  reaction  being  Na2C03  +  CaCl  =  2  NaCl 
+  CaCOs,  as  is  generally  the  case  where  these  substances 
are  brought  in  contact  with  each  other  in  somewhat  equal 
molecular  concentrations,  the  reverse  reaction  took  place, 
forming  black  alkali  and  calcium  chloride.  As  seen  in 
the  above  table  of  solubilities,  calcium  chloride  is  very 
soluble  and  might  easily  be  washed  from  the  soil  so  that 
the  above  reaction  might  under  certain  conditions  result 
in  the  formation  of  considerable  black  alkali.  In  like 
manner,  other  apparently  stable  salts  might,  by  changes 
in  molecular  concentrations,  react  to  form  new  substances 
not  possible  under  ordinary  conditions,  and  in  case  one  or 
both  of  the  end  products  were  taken  from  the  active  mass, 
there  might  be  a  profound  change  in  the  composition  of 
the  chemical  compounds. 

California  experiments  (4)  show  that  up  to  a  strength 
of  about  4000  parts  per  million  of  sodium  sulphate,  this 


ABSORPTION  OF   SALTS  BY  SOILS  109 

substance  could  be  made  to  change  into  sodium  carbonate 
in  the  presence  of  precipitated  calcium  carbonate  through 
which  carbon  dioxide  was  being  forced,  but  that  the  action 
was  most  vigorous  when  the  strength  of  sodium  sulphate 
was  only  750  parts  per  million.  This  is  the  probable  ex- 
planation of  the  fact  discovered  by  certain  investigators  (5) 
that  black  alkali  was  formed  about  the  roots  of  plants 
growing  on  white  alkali.  The  carbon  dioxide  given  off 
by  the  roots  of  the  plants  made  the  calcium  carbonate 
soluble  so  that  it  would  react  with  the  white  alkali  to  form 
the  black. 

Salts  concentrated  in  some  part  of  the  soil  by  former 
reactions  might  be  acted  upon  by  solutions  borne  from  dif- 
ferent sections  containing  other  types  of  salts  making 
possible  incessant  and  complete  exchanges  of  ions  of  the 
different  salts.  Referring  again  to  the  table  of  solubil- 
ities, it  is  seen  that  salts  do  not  maintain  the  same  relative 
solubility  at  all  temperatures.  This  disturbs  the  equi- 
librium as  the  temperature  of  the  soil  changes. 

Absorption  of  Salts  by  Soils.  —  The  alkali  problem  would 
be  much  simplified  if  the  soluble  salts  were  simply  held 
in  the  active  part  of  the  soil  solution.  With  such  a  con- 
dition it  would  take  but  a  few  leachings  of  the  soil  to  free 
it  of  excessive  salts.  Through  absorption  and  adsorption, 
however,  the  soil  tends  to  hold  part  of  the  salts  when  it  is 
drained.  With  high  concentrations  the  soil  has  little 
power  to  hinder  free  movement  of  salts,  but  with  lower 
concentrations  the  soil  retains  a  larger  proportion  of  the 
salts. 

Part  of  this  difficult  movement  is  thought  by  some  to  be 
caused  by  a  mechanical  adherence  of  the  salts  immediately 
in  contact  with  the  soil  particles;  others  consider  that  an 
actual  chemical  reaction  takes  place.  If  no  chemical 


110    CHEMICAL  EQUILIBRIUM  AND  ANTAGONISM 

reaction  occurs  the  salts  held  in  a  mechanical  manner  are 
probably  within  the  inner  circle  of  the  capillary  film  where 
very  little  movement  is  possible;  consequently,  unless 
there  is  long-continued  and  excessive  washing  of  the  soil, 
little  of  this  salt  is  lost  except  by  diffusion  which  is  a  very 


FIG.  15.  —  ALKALI  COMING  TO  THE  SURFACE  WHERE  SEEPAGE  WATER 
FROM  A  CANAL  COMES  TO  THE  SURFACE  AND  EVAPORATES.  THE  CANAL 
RUNS  THROUGH  A  SHALE  THAT  IS  HlGH  IN  SOLUBLE  SALTS. 

slow  process  in  case  the  salts  are  not  promptly  removed 
from  the  point  of  concentration.  This  adherence,  or 
adsorption,  may  account  for  the  great  quantities  of  salts 
that  are  slowly  yielded  to  water  leaching  through  soils. 
As  more  and  more  of  the  salts  are  given  up  to  the  solution 
and  carried  away,  the  remaining  portion  is  with  greater 
and  greater  difficulty  yielded  to  the  free,  or  percolating, 
water.  Because  of  the  greater  surface  exposed,  fine  clays, 
loams,  and  soils  rich  in  organic  matter  hold  the  salts  by 
absorption  more  tenaciously  than  the  coarser-grained  sands. 
Soils  such  as  the  clays,  which  are  high  in  colloidal  ma- 
terial, are  also  affected  by  an  interchange  of  ions.  The 


EQUILIBRIUM  IN  SOIL  SOLUTION  111 

colloidal  material  appears  to  be  in  weak  chemical  com- 
bination with  certain  bases.  When  the  alkali  salts  are 
brought  in  contact  with  these  colloids,  there  is  an  apparent 
exchange  of  the  sodium  of  the  alkali  for  calcium  or  mag- 
nesium. The  calcium  and  magnesium  appear  in  the 
drainage  water  in  greater  quantities  where  the  alkali  is 
present  than  where  it  is  not,  and  the  sodium  is  recovered 
only  with  great  difficulty  if  at  all  by  leaching.  This  ac- 
tion is  apparently  selective  in  nature.  The  weaker  acids 
yield  their  sodium  to  the  colloids  much  more  easily  than 
do  the  stronger  ones,  so  that  where  equal  quantities  of 
each  of  the  salts  are  added  to  a  soil  when  recovered  the 
quantity  of  acid  assignable  to  each  base  will  be  different. 
Each  soil,  and  different  parts  of  the  same  soil,  frequently 
differ  considerably  so  that  this  interchange  may  vary  both 
in  nature  and  magnitude  in  soils  not  greatly  differing  from 
each  other.  The  colloids  of  organic  matter  act  much  the 
same  as  those  of  the  soil  so  that  added  organic  matter  may 
change  the  nature  of  an  alkali  soil.  Whether  it  is  due  to 
this  exchanging  of  sodium  for  calcium  in  the  colloids  and 
the  consequent  precipitation  of  calcium  carbonate  when 
sodium  carbonate  is  added  to  soils  rich  in  colloids  or  in 
organic  matter  is  not  known,  but  much  of  the  alkalinity 
of  sodium  carbonate  disappears  when  added  to  such  soils. 
In  sand  where  colloids  and  organic  matter  are  absent, 
practically  all  of  the  carbonates  added  can  be  recovered 
by  extraction  with  water. 

Equilibrium  in  Soil  Solution.  —  That  a  complete  state 
of  equilibrium  is  ever  established  in  a  soil  is  hardly  probable. 
The  constant  removal  of  water  by  plants,  evaporation 
from  the  surface  of  the  soil,  addition  of  water  by  rains  or 
irrigation,  percolation  of  free  water,  and  all  the  other  causes 
of  movement  of  water  in  the  soil,  cause  an  incessant 


112    CHEMICAL  EQUILIBRIUM  AND  ANTAGONISM 

change  in  the  position  of  the  soluble  salts.  Layers  of 
compact  soil  or  heavy  clay  ordinarily  contain  more  soluble 
salts  than  looser  ones;  and  where  there  is  movement  of 
water  between  different  soil  layers,  there  is  a  change  in 
the  concentration  of  the  solution  and  reactions  take  place 
between  the  salts  which  have  been  dissolved  from  the  two 
types  of  soil.  Small  quantities  of  alkali  in  the  irrigation 
water  may  cause  profound  changes  in  the  chemical  com- 
position of  the  soil  solution.  Changes  in  temperature 
cause  changes  in  the  solubility  of  salts  so  that  salts  may  be 
thrown  out  of  solution  or  new  ones  brought  into  solution. 
Carbon  dioxide  and  oxygen  are  frequently  brought  into 
the  soil  by  rains,  and  carbon  dioxide  is  constantly  being 
formed  in  soils.  This  disturbs  equilibrium  of  the  com- 
pounds by  changing  the  solubility  or  causing  the  oxidation 
of  certain  compounds.  These  and  numerous  other  factors 
cause  the  soil  solution  constantly  to  vary  in  concentration 
and  composition. 

Ifi  studying  alkali,  however,  these  minute  and  trouble- 
some changes  are  not  ordinarily  of  sufficient  importance 
to  warrant  consideration.  The  quantity  of  alkali  when 
it  becomes  troublesome  is  generally  so  large  that  small 
changes  are  practically  negligible.  Changing  a  few  pounds 
to  the  acre  of  sodium  chloride  into  calcium  chloride  would 
make  so  little  difference  in  the  toxicity  of  the  alkali  that 
it  could  not  be  noticed. 

With  sodium  carbonate  the  condition  is  somewhat  dif- 
ferent. This  salt  is  relatively  unstable  when  compared 
with  sodium  chloride  and  sodium  sulphate.  In  the  pres- 
ence of  solutions  of  carbon  dioxide,  as  found  in  the  upper 
soil,  sodium  carbonate  would  probably  form  the  unstable 
sodium  bicarbonate  to  a  considerable  extent.  Sodium 
carbonate  and  bicarbonate,  on  account  of  their  solubility, 


ANTAGONISM   BETWEEN  ALKALI  SALTS      113 

react  readily  with  other  salts  and  may  form  the  relatively 
insoluble  carbonates.  The  well-known  reaction  Na2C03 
+  CaSO4  =  Na2SO4  +  CaC03,  or  the  conversion  of  black 
alkali  into  white,  is  of  the  latter  type  of  change.  Black 
alkali,  however,  is  thought  to  remain  practically  in  fairly 
stable  equilibrium  where  the  soil  has  become  so  puddled 
that  air  and  carbon  dioxide  are  largely  excluded.  Puddling 
the  soil  apparently  causes  the  conversion  of  sodium  nitrate 
into  sodium  carbonate  where  the  conditions  are  favorable, 
but  this  reaction  is  rapidly  brought  to  an  end  because  of 
lack  of  sodium  nitrate  or  the  other  agents  under  ordinary 
conditions. 

Antagonism  between  Alkali  Salts.  —  In  some  of  the  early 
work  of  Kearney  and  Cameron  (5)  it  was  noticed  that 
plants  grown  in  solutions  of  single  salts  common  in  alkali 
soils  showed  a  much  greater  toxic  effect  for  magnesium 
sulphate  and  magnesium  chloride  than  for  the  sodium  salts 
which  ordinarily  cause  the  greatest  trouble  on  alkali  land. 
When  there  were  two  salts,  especially  where  one  was  a 
calcium  salt,  in  the  same  solution,  however,  the  toxic 
effect  was  not  the  sum  of  the  two  separate  toxicities  but 
was  in  some  cases  considerably  less.  This  ameliorating 
or  antagonistic  effect  was  shown  differently  for  different 
combinations  of  salts  and  for  different  concentrations  of 
the  same  combinations;  but  the  greatest  effect  was  for 
combinations  containing  calcium  and  magnesium.  The 
antagonism  between  magnesium  sulphate  and  calcium 
sulphate  was  particularly  strong  and  led  to  the  belief  that 
a  specific  balance  between  calcium  and  magnesium  must 
exist  for  proper  growth  of  plants  despite  the  fact  that  in 
soils  such  a  relationship  did  not  exist.  Some  of  the 
ameliorating  effect,  such  as  that  where  calcium  chloride 
and  sodium  carbonate  were  in  the  same  solution,  might 


114    CHEMICAL  EQUILIBRIUM  AND  ANTAGONISM 

be  assigned  to  the  formation  of  new  and  less  toxic  com- 
pounds; but  magnesium  sulphate  with  sodium  sulphate, 
sodium  sulphate  with  magnesium  chloride,  sodium  chloride 
with  magnesium  sulphate,  and  similar  combinations  which 
exist  as  stable  compounds  in  contact  with  each  other 
were  also  corrective  of  each  other.  It  was  further  found 
that  when  the  different  salts  were  present  in  certain  pro- 
portion to  each  other  the  effect  was  different  than  where 
other  apparently  less  toxic  proportions  were  used.  When 
398  parts  per  million  of  sodium  carbonate  and  710  parts 
per  million  of  sodium  sulphate  were  in  the  same  solution, 
some  of  the  plants  lived;  but  when  the  sodium  sulphate 
was  reduced  to  half  this  quantity,  all  the  plants  died. 

A  number  of  other  experimenters  have  noticed  the 
antagonistic  action  between  calcium  and  magnesium  salts 
when  in  solutions  with  sodium  salts.  Miyake  (16),  work- 
ing with  rice  plants,  found  that  there  was  a  slight  antago- 
nism between  the  monovalent  anion,  chloride,  and  the 
divalent  anion,  sulphate,  but  it  was  small  compared  with 
that  between  the  cations.  He  found  potassium  antago- 
nistic to  sodium  when  the  two  salts  were  together  in  the 
form  of  sulphates,  chlorides,  or  nitrates. 

The  quantity  of  salts  which  caused  injury  to  the  plants 
growing  in  the  solutions  of  these  experiments  is  much  be- 
low the  quantities  ordinarily  found  to  cause  injury  in  field 
or  soil  experiments,  especially  where  the  unmixed  solutions 
were  used.  It  has  been  suggested  that  the  reason  for  the 
lower  toxicity  in  the  soils  is  because  the  soil  contains  cal- 
cium and  other  salts  which  ameliorate  the  effect  of  the 
injurious  salts.  Whether  this  explanation  is  sufficient  to 
account  for  all  of  the  difference  is  questionable,  however. 
That  lime  is  a  good  corrective  for  magnesium,  as  reported 
above,  is  shown  by  the  fact  that  certain  Canadian  soils  (19) 


ANTAGONISM  BETWEEN  ALKALI  SALTS      115 

containing  50,000  parts  per  million  of  magnesium  sulphate 
were  made  to  produce  much  better  growth  by  adding 
lime  than  without  it.  Most  alkali  soils  contain  consider- 
able lime.  This  may  account  for  the  large  quantities  of 
alkali  sometimes  present  without  serious  injury  to  crops 
growing  upon  them. 

The  work  of  Lipman  and  Gericke  (n)  indicates  that 
even  in  a  clay  soil  of  the  arid  region  there  was  antagonism 


• 


;••••  •  '.^«*^^^^SSMHH»HHHBWBBBR»?sL  •-** — —..*«•  ^ — — J 

FIG.  1 6.  —  BLACK  ALKALI  CRUST  FORMING  WHERE  THE  LAND 
HAS  BEEN  WET. 

between  sodium  chloride  and  sodium  sulphate,  and  be- 
tween sodium  chloride  and  sodium  carbonate  in  the  second 
crop  of  barley,  although  none  was  shown  in  the  first. 
That  the  time  of  contact  might  have  had  some  effect  is 
shown  from  the  observation  that  neither  sodium  chloride 
nor  sodium  sulphate  was  stimulating  in  concentration  of 
icoo  parts  per  million  for  the  first  crop  but  were  toxic 
for  the  second.  Calcium  sulphate  was  antagonistic  even 
in  comparatively  small  quantities  when  added  to  a  soil 
containing  4000  parts  per  million  of  sodium  sulphate. 

Lipman  and  Sharp  (14),  in  an  experiment  with  a  natural 
soil  containing  6400  parts  per  million  of  total  salts  com- 


116    CHEMICAL  EQUILIBRIUM  AND  ANTAGONISM 

posed  of  4590  parts  per  million  sodium  chloride,  980  parts 
per  million  sodium  sulphate,  and  830  parts  per  million  of 
sodium  carbonate,  found  that  applying  sulphuric  acid  at 
the  rate  of  about  119  parts  per  million  was  especially  bene- 
ficial, and  up  to  about  451  parts  per  million,  the  highest 
quantity  added,  the  treatment  was  beneficial.  Gypsum 
also  caused  a  higher  yield  of  barley.  The  treatments  were 
thought  to  be  helpful  both  by  neutralizing  the  sodium  car- 
bonate and  also  by  causing  a  beneficial  shrinkage  of  colloids. 

A  number  of  investigators  have  noted  an  antagonistic 
effect  of  the  heavier  metals,  such  as  calcium,  copper,  and 
zinc,  on  the  common  alkali  salts.  Caldwell  (i)  thinks 
from  his  observations  that  this  antagonistic  effect  is  due 
to  a  dilution  of  the  active  salts  and  not  to  an  actual  an- 
tagonism. He  did  not  find  an  antagonistic  action  between 
sodium  and  potassium,  but  on  the  contrary  he  found  a 
decrease  in  the  stimulating  effect  when  certain  concentra- 
tions of  potassium  salts  were  diluted  with  sodium  salts. 
Ammonia  and  sodium  in  the  proportion  of  i  to  i  gave  the 
best  growth  in  highly  concentrated  solutions. 

The  author  (3)  found  the  antagonistic  effect  in  solution 
cultures  to  be  greater  than  when  the  same  mixtures  were 
present  in  soils. 

Some  of  the  most  positive  antagonistic  results  in  soils 
appear  in  the  work  of  Lipman  and  his  associates  on  soil 
bacteria.  On  the  ammonification  organisms  he  (9)  found, 
no  antagonism  between  mangesium  and  calcium  nor  be- 
tween sodium  and  calcium,  but  there  was  an  antagonistic 
effect  both  for  these  and  the  nitrifying  organisms  when  any 
two  of  the  three  alkali  salts  —  sodium  chloride,  sodium 
carbonate,  and  sodium  sulphate  —  were  in  the  soil  together. 
There  was  antagonism  between  toxic  as  well  as  between 
stimulating  concentrations  of  these  salts.  The  nitrogen- 


REFERENCES  117 

transforming  powers  of  the  soil  were  better  than  the  checks 
when  two  salts,  one  of  which  was  present  in  toxic  quantities, 
were  present  in  the  soil,  or  where  both  were  in  toxic 
quantities  for  the  single  salts.  The  nitrogen-fixing  or- 
ganisms showed  slight  antagonism  except  between  sodium 
sulphate  and  sodium  carbonate  which  showed  no 
antagonism. 

The  exact  cause  of  antagonism  between  the  ions  has 
not  been  fully  explained.  Osterhout  (17)  found  the 
permeability  of  the  protoplasm  was  rapidly  increased  until 
death  occurred  when  in  solutions  of  sodium  chloride. 
With  calcium  chloride  the  permeability  decreased  to  a 
certain  point  after  which  it  increased  as  with  sodium 
chloride  until  death  occurred.  He  thinks  that  when  a 
substance  like  sodium  chloride  is  brought  in  contact  with 
one  like  calcium  chloride  where  the  tendency  is  to  cause 
permeability  in  opposite  directions,  there  is  an  antag- 
onistic effect.  He  (17)  thinks  this  interference  of  the  ions 
of  the  salts  attempting  to  enter  the  cell  may  be  the  real 
cause  of  the  antagonism.  Hansteen  (2)  thinks  calcium 
acts  as  an  external  protection  to  the  roots  of  the  plants, 
which  is  essentially  that  of  the  above  view.  Le  Clerc  and 
Breazeale  (8)  claim  that  lime  overcomes  the  toxic  effect 
of  the  sodium  salts  without  preventing  the  absorption  of 
sodium  chloride  by  the  plant. 

REFERENCES 

1.  CALDWELL,  J.  S.     The  Effect  of  Antagonistic  or  Balanced  Solutions 

containing  Sodium  Chloride  together  with  One  of  the  Chlorides  of 
Calcium,  Magnesium,  Potassium,  Strontium,  Ammonium,  or  Copper 
upon  the  Growth  of  Corn  Plants  Rooted  in  an  Artificial  Soil.  Sci. 
n.  ser.  39  (1914),  P-  293. 

2.  HANSTEEN,  B.     The  Relation  of  Plants  to  Certain  Salts,  I  and  II. 

Jahrb.  wiss  Bot.  (Pringsheim) ,  47  (1910),  No.  3.  nn.  287-376.  (Abs. 
E.  S.  R.  23,  p.  328.) 


118    CHEMICAL  EQUILIBRIUM  AND  ANTAGONISM 

3.  HARRIS,  F.  S.     Effect  of  Alkali  Salts  in  Soils  on  the  Germination  and 

Growth  of  Crops.     Jour.  Agr.  Res.  5  (1915),  pp.  1-53. 

4.  JOFFA,  M.  B.     Reaction  between  Alkali  Sulphates,  Carbonates,  and 

HCO3.     Cal.  Sta.  Rpt.  1890,  pp.  100-105. 

5.  KEARNEY,  T.  H.,  and  CAMERON,  F.  K.     Some  Mutual  Relations  be- 

tween Alkali  and  Vegetation.     U.  S.  D.  A.  Rpt.  71  (1902),  78  pp. 

6.  KELLEY,   W.   P.     Action  of   Precipitated   Magnesium   Carbonate  in 

Soils.     Jour.  Am.  Soc.  Agron.  9  (1917),  pp.  285-297. 

7.  KNIGHT,  H.  G.,  and  MOUDY,  R.  B.     Alkali  Studies,  VI.     Wyo.  Sta. 

Rpt.  1906,  pp.  45-51. 

8.  LE  CLERC,  J.  A.,  and  BREAZEALE,  J.  F.     The  Effect  of  Lime  upon  the 

Alkali  Tolerance  of  Wheat  Seedlings.  Orig.  Commun.  8  Intn. 
Cong.  Appl.  Chem.  (Washington  and  New  York),  26  (1912),  sect. 
Vla-XIb,  App.  p.  135.  (Abs.  E.  S.  R.  29,  p.  322.) 

9.  LIPMAN,  C.  B.     Antagonism  between  Salts  as  Affecting  Soil  Bacteria. 

Sci.  n.  ser.  39  (1914),  p.  764.     See  also  Bot.  Gaz.  Vol.  49,  p.  41. 
10.   LIPMAN,  C.  B.     Antagonism  between  Anions  as  Related  to  Nitrogen 

Transformation  in  Soils.     The  Plant  World,  17  (1914),  pp.  295-305. 
n.   LIPMAN,  C.  B.,  and  GERICK,  W.  F.     Antagonism  between  Anions  as 

Affecting   Barley  Yields  on  a  Clay  Adobe  Soil.     Jour.  Agr.  Res. 

4  (1915),  pp.  201-218. 

12.  LIPMAN,  C.  B.,  and  GERICK,  W.  F.     Copper  and  Zinc  as  Antagonistic 

to  Alkali  Salts  in  Soils.     Am.  Jour.  Bot.  5  (1918),  pp.  151-170. 

13.  LIPMAN,  C.  B.,  and  BURGESS,  P.  S.     Antagonism  between  Anions  as 

Affecting  Soil  Bacteria,  III.  Nitrification.  Centrbl.  f.  Bakt.  Abt. 
42  (1914),  Nos.  17,  18,  pp.  502-509.  (Abs.  E.  S.  R.  33,  p.  323.) 

14.  LIPMAN,  C.  B.,  and  SHARP,  L.  T.     New  Experiments  on  Alkali  Soil 

Treatment.  Univ.  Cal.  Pub.  Agr.  Sci.  9  (1915),  No.  9,  pp.  275- 
290. 

15.  MARQUENNE,  L.,  and  DEMOUSSY,  E.    The  Influence  of  Salts  on  Vari- 

ous Metals  on  Germination  in  the  Presence  of  Calcium.  Comp. 
Rend.  Acad.  Sci.  (Paris),  166  (1918),  pp.  89-92.  (Abs.  E.  S.  R. 
39,  p.  526.) 

16.  MIYAKE,  K.     Influence  of  the  Salts  Common  in  Alkali  Soils  upon  the 

Growth  of  Rice  Plants,  I-IV.  Bot.  Mag.  (Tokio),  27  (1913),  pp.  173- 
182,  193-204,  224-233,  268-270  (Abs.  E.  S.  R.  30,  p.  630);  Jour. 
Biol.  Chem.  16  (1913),  pp.  235-263  (Abs.  E.  S.  R.  30,  p.  833); 
Bot.  Mag.  Tokio,  28  (1914),  pp.  1-4. 

17.  OSTERHOUT,  W.  J.  V.    The  Permeability  of  Protoplasm  to  Ions  and 

the  Theory  of  Antagonism.     Sci.  n.  ser.  35  (1912),  pp.  156-157. 

1 8.  OSTERHOUT,  W.   J.  V.     Antagonism   and  Permeability.     Sci.  n.  ser. 

45  (1917),  pp.  97-103. 

19.  SHUTT,  F.  T.    Alkaline  Soils  of  Canada.    Can.  Exp.  Farms  Rpt.  1893, 

pp.  135-140. 


CHAPTER  IX 

RELATION   OF   ALKALI  TO   PHYSICAL 
CONDITIONS   IN   THE   SOIL 

THE  entire  physical  condition  of  the  soil  is  changed  by 
the  presence  of  large  quantities  of  certain  soluble  salts. 
All  salts  in  fact  bring  about  some  physical  changes  but 
certain  of  the  alkali  salts,  particularly  the  carbonates, 
cause  complete  transformations.  Each  soluble  salt  that 
is  present  in  large  quantity  produces  some  typical  con- 
dition, which  is  usually  bad.  The  effect  of  one  salt  may 
be  in  part  neutralized  by  another,  so  that  the  final  effect 
is  somewhat  uncertain.  It  depends  on  the  nature  of  the 
soil  and  on  the  combination  and  concentration  of  the  salts 
present. 

The  chief  manifestations  of  salts  on  the  physical  con- 
dition of  the  soil  are:  (i)  The  change  in  structure  or  tilth; 
(2)  an  altering  of  the  colloidal  substances;  (3)  the  forma- 
tion of  a  hardpan;  and  (4)  a  change  in  the  moisture  re- 
lations. 

Changing  Soil  Structure.  —  The  tilth,  or  structure,  of  a 
soil  has  much  to  do  with  its  crop-producing  power.  Soils 
containing  an  equal  amount  of  plant-food  may  vary 
greatly  in  their  power  to  yield.  The  soil  must  do  more 
than  furnish  a  supply  of  food  for  growing  plants;  it  must 
also  be  a  good  home  for  them.  Plants,  like  animals,  even 
though  they  have  sufficient  food  to  nourish  them  will  not 
thrive  unless  other  factors  affecting  growth  are  favorable. 
Air  must  be  present  for  the  roots,  and  the  soil  particles 

119 


120      RELATION    TO    PHYSICAL    CONDITIONS 

should  be  so  arranged  that  the  roots  may  easily  secure 
food  and  moisture. 

Soils  vary  greatly  in  their  tilth.  Those  made  up  of 
coarse-grained  particles  are  less  affected  in  structure  by 
various  agencies  than  those  composed  of  fine-grained 
particles.  With  coarse-grained  soils  the  keeping  of  a  good 
tilth  presents  no  serious  problem.  With  fine-grained  soils, 
on  the  other  hand,  the  maintaining  of  a  good  structure 
requires  constant  attention.  It  may  be  affected  by  several 
factors,  one  of  which  is  the  presence  of  soluble  salts. 

The  ideal  structure  is  usually  one  in  which  there  is  a 
maximum  of  air  space.  This  condition  also  favors  the 
various  cultural  operations.  If  fine  soil  particles  are 
packed  tightly  together,  there  is  not  sufficient  air  space 
for  the  best  root  development  and  the  soil  is  difficult  to 
till.  When  plowed,  it  becomes  cloddy  instead  of  mellow. 
In  order  to  secure  the  best  condition,  the  fine  particles 
should  be  clustered  together,  or  flocculated.  This  gives 
air  space  between  the  groups  of  particles  as  well  as  be- 
tween the  individual  particles  in  the  group  and  establishes 
lines  of  weakness  in  all  directions.  This  enables  the  soil 
to  break  up  readily  into  a  crumb-like  structure  when  cul- 
tivated instead  of  into  clods.  Anything  that  promotes 
flocculation  improves  tilth;  likewise  anything  that  pro- 
motes deflocculation  injures  tilth. 

The  effect  of  soluble  salts  on  tilth  has  been  a  subject  of 
considerable  study.  Sachsse  and  Becker  (17)  showed  that 
nitrate  of  soda  not  only  prevented  flocculation  but  also 
separated  floccules  that  had  already  been  formed.  It 
was  thought  that  this  result  might  be  due  in  part  to  the 
formation  in  the  soil  of  carbonate  of  soda,  which  in  turn 
acts  upon  the  hydrated  silicates,  producing  colloidal  sili- 
cates which  reduce  the  permeability  of  the  soil  to  water. 


CHANGING    SOIL    STRUCTURE  121 

Hall  (10)  found  that  when  nitrate  of  soda  was  applied  in 
large  quantities  to  heavy  soils  at  Rothamsted  the  tilth 
of  the  land  was  destroyed.  He  concluded  that  this  result 
came  about  by  the  production  of  the  deflocculating  salt, 
sodium  carbonate. 

The  presence  of  alkali  salts  was  early  observed  by 
Loughridge  (15)  and  Hilgard  (13)  to  have  a  bad  effect 
on  the  soil  by  puddling  or  deflocculating  the  particles 
and  a  consequent  compact  condition  which  prevents  the 
rapid  rise  of  water.  Puddling  was  accompanied  by  large 
contraction  of  volume.  A  similar  action  particularly  in 
clays  was  also  observed  by  Bemmeln  (i). 

Masoni  (16)  showed  that  not  all  soluble  salts  have  a 
deflocculating  effect.  Some  of  them  have  a  decidedly 
flocculating  effect  which  is  not  dependent  on  the  quantity 
of  salt  but  rather  on  ionic  concentration  and  the  degree 
of  dissociation.  He  considers  the  flocculating  power  to 
be  a  function  of  the  cation,  the  anion  being  without  in- 
fluence. If  the  value  of  the  flocculating  power  for  the 
sodium  ion  be  taken  as  i,  then  for  the  potassium  or  am- 
monium it  is  2.4,  and  for  the  calcium  ion  5.7. 

Free  (7)  has  pointed  out  that  flocculation  and  defloccula- 
tion  are  relative  terms  and  that  the  action  of  salts,  acids, 
and  alkalies  in  this  connection  are  twofold  and  depend 
on  the  mutual  interpenetration  of  particle  and  medium 
and  on  the  electrical  charge  on  the  surface  of  the  particle. 

Davis  (6)  has  shown  that  even  small  quantities  of  soluble 
salts  are  important  in  modifying  the  physical  properties 
of  the  soil  including  the  apparent  specific  gravity  which  is 
affected  directly  by  the  flocculation  of  the  particles.  The 
effect  of  salts  is  shown  to  be  very  much  greater  in  soils  of 
finer  particles  than  in  sands.  It  is  usually  in  the  finer, 
heavier  soils  that  alkali  is  found ;  consequently,  it  is  usually 
only  in  these  soils  that  the  problem  becomes  troublesome. 


122      RELATION    TO   PHYSICAL    CONDITIONS 

The  acute  form  of  deflocculation  manifests  itself  in  the 
crust  at  the  surface  of  the  soil  resulting  from  sodium  car- 
bonate or  black  alkali.  Only  slightly  less  troublesome  is 
the  brown  crust  found  where  large  quantities  of  sodium 
nitrate  are  present.  Where  these  crusts  are  found  it  be- 
comes almost  impossible  to  raise  crops  successfully.  Not 
only  is  the  land  difficult  to  till  but  the  crust  that  may 
form  after  a  tender  plant  come's  up  is  so  hard  that  the 
plant  cannot  make  a  normal  growth.  There  is  an  actual 
physical  impediment  in  addition  to  any  chemical  corroding 
which  the  salt  may  exert  on  the  plant. 

Effect  of  Colloids.  —  All  agricultural  soils  contain  some 
particles  called  colloids  so  small  that  they  have  properties 
entirely  different  from  the  larger  particles.  The  colloidal 
material  acts  somewhat  like  dissolved  salts  and  yet  it 
obeys  some  of  the  laws  that  apply  to  the  larger  particles. 
During  recent  years  it  is  being  recognized  that  many  of 
the  effects  of  alkalies  on  the  physical  conditions  of  soils 
come  about  through  this  colloidal  material. 

Kellerman  (12)  showed  that  the  impermeable  condition 
of  an  alkali  soil  at  Fallon,  Nevada,  was  due  largely  to  the 
condition  of  the  colloidal  matter  in  the  soil. 

Gedroits  (9),  as  a  result  of  extensive  experiments  on  the 
relation  of  salts  to  soil  colloids,  found  that  many  of  the 
physical  changes  ordinarily  brought  about  in  soils  by 
salts  come  from  their  effect  on  colloids. 

Important  as  are  the  investigations  already  made  on 
the  relation  between  alkali  and  soil  colloids,  they  may  be 
considered  as  only  pioneer  work  in  view  of  what  the  future 
promises. 

Hardpan.  —  Under  the  surface  of  many  of  the  soils  in 
arid  regions,  particularly  in  sections  of  abundant  alkali,  a 
hard  layer  is  found  which  obstructs  the  .penetration  of 


HARDPAN  123 

both  roots  and  water.  Hardpans  are  not  always  caused 
by  alkali,  but  are  more  likely  to  be  formed  if  it  is.  present. 
Hardpan  differs  from  the  ordinary  impervious  subsoil  in 
that  it  has  a  limited  thickness,  usually  varying  from  2  to 
1 8  inches  with  an  average  of  3  to  6  inches.  A  good  ex- 
ample is  described  by  Gardner  and  Stewart  (8) .  A  num- 
ber of  explanations  of  the  genesis  of  hardpans  have  been 
given. 

Hilgard  (13)  has  the  following  to  say  about  the  cause  of 
hardpan:  "The  recognition  of  the  cause  of  hardpan  is  of 
considerable  importance  to  the  farmer  because  of  the  in- 
fluence of  the  nature  of  the  cement  and  the  causes  of  its 
formation  upon  the  possibility  and  methods  of  its  de- 
struction, for  the  improvement  of  the  land. 

"It  may  be  said  in  general  that  inasmuch  as  the  cause 
of  the  formation  of  hardpan  is  a  stoppage  of  the  water  in 
its  downward  penetration,  the  reestablishment  of  that  pene- 
tration will  tend  to  prevent  additional  induration;  more- 
over, experience  proves  that  whenever  this  is  accomplished 
even  locally,  as  around  a  fruit  tree  in  an  orchard,  the  hard- 
pan  gradually  softens  and  disappears  before  the  frequent 
changes  in  moisture  conditions  and  the  attack  of  roots. 
The  use  of  dynamite  for  this  purpose  in  California  has 
already  been  referred  to;  it  seems  to  be  the  only  resort 
when  the  hardpan  lies  at  a  considerable  depth.  When  it 
is  within  reach  of  the  plow,  it  may  be  turned  up  on  the 
surface  by  the  aid  of  a  subsoiler  and  will  then  gradually 
disintegrate  under  the  influence  of  air,  rain,  and  sun. 
But  when  the  hardpan  is  of  the  nature  of  moorbedpan, 
containing  much  humic  acid  and  perhaps  underlaid  by 
bog-iron  ore,  the  use  of  lime  on  the  land  is  indicated,  and 
will  in  the  course  of  time  destroy  the  hardpan  layer.  This 
is  the  more  desirable  as  in  such  cases  the  surface  soil  is. 


124      RELATION   TO    PHYSICAL    CONDITIONS 

usually  completely  leached  of  its  lime  content,  and  is  con- 
sequently extremely  unthrifty." 

Cameron  (5)  gives  the  following  explanation  of  the  origin 
of  hardpans:  "The  application  of  the  present  views  re- 
garding solutions  to  the  study  of  hardpan  phenomena  gives 
promise  of  valuable  as  well  as  interesting  results.  A  hard- 
pan  may  be  defined  as  a  layer  of  the  soil,  usually  near  the 
surface,  having  the  texture  of  the  soil  just  above  and  below 
it,  but  more  or  less  closely  cemented  by  some  material. 
In  general,  hardpan  is  a  characteristic  of  soils  where  drain- 
age is  very  poor  or  where  standing  soil  waters  may  ac- 
cumulate. The  cementing  material  is  often  lime  carbonate, 
but  may  be  other  material,  as  the  hydrates  of  iron  and 
alumina  or  silica.  Hardpans  vary  much  in  their  physical 
properties.  They  are  sometimes  as  dense  and  close- 
grained  as  a  well-characterized  rock,  requiring  blasting  or 
similar  methods  to  break  them  up.  In  other  cases  they 
may  be  partly  porous,  and  when  brought  to  the  surface 
disintegrated  with  ease,  and  there  are  all  grades  between 
these  extremes. 

"The  objections  to  their  presence  in  the  soil  are  evident. 
They  prevent  the  penetration  of  plant  roots,  and,  more 
important,  they  prevent  the  moisture  from  rain,  irriga- 
tion, etc.,  sinking  into  the  soil  and  thus  being  conserved  for 
future  use.  They  also  prevent  the  water  that  may  be 
beneath  them  from  being  drawn  to  the  surface  and  made 
available  for  the  plants. 

"The  formation  of  a  calcium  carbonate  hardpan  is  the 
most  readily  understood,  and  this  has  been  dwelt  upon  at 
some  length  in  a  paper  by  Gardner  and  Stewart  (8).  It 
is  there  pointed  out  that  resolution  and  reprecipitation 
are  important  factors.  But  when  the  calcium  carbonate 
does  not  exist,  as  such,  in  the  soil  or  in  the  vicinity,  so  as 


HARDPAN  125 

to  be  brought  by  water,  while  a  limestone  hardpan  might 
form,  under  favorable  conditions,  it  seems  more  probable 
that  the  cementing  material  would  be  one  of  the  other 
substances  mentioned,  or  a  mixture  of  them. 

"The  mineral  constituents  of  the  soil  are  for  the  most 
part  salts,  but  with  a  few  exceptions  salts  with  a  very 
limited  solubility.  Nevertheless,  to  some  extent  at  least 
they  are  soluble,  as  are  other  salts,  and  their  solubility 
may  be  increased  or  diminished  by  the  presence  of  another 
salt  solute,  as  has  been  indicated  in  a  former  part  of  this 
paper.  These  salts  —  carbonates,  silicates,  aluminates, 
ferrates,  etc.  —  are  without  exception  salts  of  weak  acids 
and  may  be  expected  to  be  much  hydrolized  in  as  far  as 
they  are  soluble  at  all.  This  has  been  very  beautifully 
illustrated  in  recent  experiments  by  Clark,  who  has  treated 
a  large  number  of  minerals  carefully  pulverized  with  pure 
water.  On  the  addition  of  a  few  drops  of  dilute  alcoholic 
phenolphthalein  a  marked  alkaline  reaction  could  be  ob- 
served in  the  great  majority  of  the  cases  investigated. 
The  reaction  may  be  indicated  thus,  assuming  a  very 
simple  example  to  exist: 

RSi03  +  HOH^ROH  +  H2SiO3. 

"All  these  other  substances  are  very  slightly  ionized 
in  comparison  with  ROH.  If  R  be  a  well-marked  base, 
such  as  sodium  or  calcium,  the  solution  will  therefore  be 
alkaline,  as  has  been  shown  to  be  the  case  with  calcium 
carbonates,  sodium  silicates,  etc.  The  fact  that  the 
silicate  is  complex  will  not  alter  this  general  property. 
Precisely  similar  conduct  is  to  be  expected  of  aluminates 
and  ferrates.  This  means  that  there  will  actually  exist 
in  the  solution  some  of  the  hydrates  of  alumina,  silica,  or 
iron,  as  the  case  may  be,  which  will  remain  as  such  on 
evaporation,  though  the  absolute  amount  may  be  very 


126      RELATION   TO   PHYSICAL    CONDITIONS 

small.  The  bases  will  be  more  or  less  readily  removed,  as 
they  will  be  brought  in  contact  with  the  carbonic  acid  and 
other  acids  (organic?)  of  the  soil  to  form  comparatively 
readily  soluble  salts. 

"This  process  probably  plays  an  important  part  in  the 
formation  of  bog-iron  ore,  which  may  be  regarded  as 
strictly  analogous  to  a  hardpan.  The  deposition  of 
bauxite,  for  example,  or  the  formation  of  a  silicious  con- 
glomerate is  essentially  of  the  same  nature.  But  it  should 
be  remembered  that  in  these  latter  cases  when  the  action 
has  been  deep-seated  with  hot  water  as  the  solvent,  the 
reagent  has  been  much  more  ionized  and  so  is  much  more 
efficient  as  a  solvent. 

"An  interesting  case  from  southern  California  has  re- 
cently come  to  our  attention.  The  soil  was  shown  to  have 
been  somewhat  compacted  under  the  plow  sole.  When 
the  irrigating  water  was  applied,  this  packed  region  of  the 
soil  caused  a  more  or  less  temporary  accumulation  of  the 
waters.  This  soil,  as  can  be  readily  seen  under  the  micro- 
scope, contains  a  large  proportion  of  unaltered  mineral 
fragments,  rich  in  iron  and  alumina  and  therefore  well 
adapted  to  yielding  these  materials  under  -the  influence 
of  the  solvent  action  of  the  water;  and,  as  a  matter  of 
fact,  this  packed  material  is  found  to  rapidly  become 
cemented  with  iron  and  alumina,  as  an  examination  in 
this  laboratory  showed.  It  is  to  be  regretted  that  at  the 
'  time  this  examination  was  in  progress  it  was  not  deemed 
expedient  to  determine  what  constituents  the  irrigating 
water  held  which  might  augment  its  solvent  power. 

"That  other  agencies  are  at  work  in  the  production  of 
these  phenomena  may  well  be  the  case.  For  instance, 
oxidations  undoubtedly  have  a  significant  role  in  this 
connection  in  breaking  up  the  original  minerals.  But  it 


HARDPAN 


127 


seems  equally  certain  that  the  part  that  solutions  play  has 
not  been  given  the  consideration  that  it  merits,  mainly 
because  solution  phenomena  have  not  been  understood 
until  comparatively  recent  years. 

"The  study  of  hardpan  formation  necessitates  a  con- 
sideration of  certain  physical  phenomena;  for  instance, 
the  movement  of  water  and  various  solutions  in  the  soil. 
This  subject  is  receiving  attention  in  this  laboratory;  but 
while  a  good  many  observations  have  been  made  and  much 
valuable  data  collected,  it  is  yet  too  soon  to  formulate  a 
complete  hypothesis  for  this  subject.  The  views  here 
described  are  put  forward  in  the  hope  of  furnishing  an  in- 
centive to  more  widespread  interest  and  work  on  this 
important  subject." 

Heileman  (12)  gives  in  Table  XVI  the  composition  of  a 
typical  hardpan  in  the  Kittitas  Valley,  Washington. 
TABLE  XVI.    COMPOSITION  OF  HARDPAN 


TOTAL  LIME  AND  MAGNESIUM  CARBONATE 
IN  HARDPAN 

WATER-SOLUBLE  SALTS  IN  HARDPAN 

Calcium  Carbonate, 
Per  cent 

Magnesium  Carbonate, 
Per  cent 

Total  Salts 
Per  cent 

Black  Alkali 
Per  cent 

White  Alkali 
Per  cent 

No.    8 

21 

46 
56 

21.15 

14-93 
21.79 
63.22 

1.72 

3-OQ 
2.97 

2-45 

•343 
.136 
•133 

•350 

.174 
.029 
.109 
•145 

.018 
.023 
.Oil 

.041 

Breazeale  (2)  shows  that  the  idea  that  hardpan  under  a 
soil  high  in  sodium  carbonate  has  resulted  from  the  sodium 
carbonate  may  not  be  true.  In  fact  the  sodium  carbonate 
accumulation  may  have  come  from  a  decomposition  of  the 
calcium  carbonate  in  the  hardpan  and  a  combination  with 
sodium  to  form  the  black  alkali.  He  succeeded  in  bringing 
about  this  interchange  in  the  laboratory. 


128      RELATION   TO    PHYSICAL    CONDITIONS 

Effect  on  Moisture  Movements.  —  The  somewhat  un- 
usual moisture  conditions  in  alkali  soils  have  long,  been 
observed  by  students  of  alkali.  Briggs  and  Lapham  (4) 
investigated  the  effect  of  various  soluble  salts  on  rate  of 
capillary  movements  through  the  soil  and  as  a  result  of 
their  studies  came  to  the  following  conclusions:  "(i)  Dis- 
solved salts  in  general  do  not  increase  the  capillary  rise  of 
soil  waters;  (2)  neutral  salts  in  dilute  solution  have  prac- 
tically no  influence  on  the  extent  of  capillary  action; 
(3)  concentrated  or  saturated  solutions  of  all  salts  materially 
diminish  capillary  activity;  (4)  this  effect  appears  to  be 
due  (a)  to  the  increased  density  of  the  solution  which 
more  than  offsets  the  increased  surface  tension,  and  (b)  to 
the  resistance  of  a  film  to  a  tangential  shearing  stress  which 
retards  capillary  action  and  offers  in  addition  a  permanent 
resistance  to  the  movement  of  the  solution  through  films, 
thus  increasing  the  angle  of  contact,  or  (e)  to  an  increase 
in  the  tension  of  the  liquid-solid  surface,  as  the  concen- 
tration is  increased;  (5)  sodium  carbonate  differs  from 
neutral  salts,  the  capillary  rise  being  considerably  greater 
than  for  neutral  solutions  of  equal  concentration;  (6)  this 
may  be  due  in  part  to  the  saponification  of  traces  of  grease 
on  the  surface  of  the  soil  grains  through  the  hydrolysis 
of  the  sodium  carbonate,  thus  forming  clean  surfaces  for 
capillary  action;  (7)  the  same  effect  should  consequently 
be  observed  with  all  salts  which  undergo  an  alkaline  hy- 
drolysis, viz.,  potassium  and  sodium  carbonates,  borates, 
phosphates,'  etc. ;  (8)  this  action  is  characterized  in  the  soil 
tubes  by  indistinctness  of  the  upper  boundary  of  the 
capillary  column." 

Capillarity  is  dependent  on  surface  tension.  Since  the 
capillarity  does  not  seem  to  be  greatly  influenced  by 
soluble  salts  it  seems  evident,  as  pointed  out  by  Davis  (6), 


EFFECT   ON    MOISTURE   MOVEMENTS       129 

that  the  profound  physical  changes  brought  about  in  the 
soil  by  alkali  are  due  largely  to  forces  other  than  surface 
tension.  This  is  illustrated  by  the  fact  that  while  in  the 
experiments  of  Briggs  and  Lapham  (4)  sodium  carbonate 
increased  the  capillary  rise  of  water,  it  is  a  well-known  fact 
in  field  practice  that  the  presence  of  large  quantities  of 
sodium  carbonate,  or  black  alkali,  interfere  with  the  pas- 
sage of  water  through  the  soil.  In  an  experiment  con- 
ducted by  the  author,  there  was  added  to  a  fertile  loam 
soil  5  per  cent  of  sodium  carbonate.  The  soil  was  then 
placed  loosely  in  percolators  so  that  the  total  depth  of 
soil  was  four  feet.  The  same  soil  containing  no  sodium 
carbonate  was  arranged  in  similar  manner.  Water  was 
then  added  to  each  soil  and  kept  six  inches  deep  over  the 
surface.  In  the  normal  soil  the  water  percolated  through 
the  four-foot  column  in  two  hours,  whereas  it  failed  to 
penetrate  the  four  feet  containing  carbonate  in  a  year. 
The  organic  matter  was  dissolved  from  the  upper  layer 
and  washed  to  a  lower  level  where  it  made  the  soil  im- 
penetrable. 

Excessive  nitrates  in  the  soil  act  in  much  the  same  way 
as  the  carbonates  except  that  the  crust  they  form  has  a 
brown,  instead  of  a  black,  color  and  it  is  not  so  im- 
penetrable. The  nitrates  also  interfere  much  less  with 
the  passage  of  water.  Alkali  spots  are  often  found  where 
the  soil  remains  permanently  dry  several  inches  below  the 
surface  even  though  irrigation  water  is  run  over  them 
every  week  for  several  months.  It  is  very  evident  there- 
fore that  though  the  salts  may  not  exert  a  strong  influence 
of  direct  capillary  action  they  do  very  materially  affect 
the  absorption  of  irrigation  and  rain  water  in  practice. 

Where  gypsum  is  present  in  large  quantities  in  an  ir- 
rigated soil,  it  is  gradually  washed  out,  causing  the  soil  to 


130      RELATION    TO    PHYSICAL    CONDITIONS 

sink  and  leave  typical  holes.  Sodium  and  magnesium 
chlorides  and  sulphates  have  less  marked,  but  very  dis- 
tinct, effects  on  moisture  movements. 

Evaporation  of  Moisture.  —  The  vapor  tension  of  water 
is  reduced  by  the  presence  of  dissolved  salts;  hence  the 
presence  of  alkali  reduces  the  rate  of  evaporation.  The 
rate  of  decrease  of  evaporation  produced  by  the  various 
salts  is  shown  by  Briggs  (3)  and  by  Harris  and  Robin- 
son (n).  It  is  not  equal  to  the  reduction  in  the  vapor 
tension  of  the  solution  since  the  air  at  all  times  contains 
some  moisture.  The  results  of  Harris  and  Robinson 
showed  an  evaporation  of  190  grams  from  distilled  water 
and  only  100  grams  from  an  equal  surface  of  water  in  which 
had  been  dissolved  30  per  cent  of  sodium  chloride.  Sand 
moistened  with  distilled  water  had  a  loss  of  80  grams, 
whereas  that  with  a  2-normal  solution  of  sodium  nitrate 
evaporated  but  53  grams  of  water. 

In  an  experiment  by  the  author  a  loam  soil,  to  which 
had  been  added  various  quantities  of  the  sodium  chloride, 
sodium  sulphate,  and  sodium  carbonate,  was  placed  in 
petri  dishes  in  a  closed  chamber  in  which  the  air  was  kept 
saturated.  The  soils  all  took  moisture  from  the  air,  the 
rate  of  absorption  depending  on  the  salt  and  the  concen- 
tration. In  the  higher  concentrations  so  much  moisture 
was  absorbed  that  free  water  covered  the  surface  of  the 
soil.  A  condition  similar  to  this  is  often  found  in  nature 
where  the  soil  of  an  alkali  spot  is  wet  constantly  during 
the  season  even  though  the  surrounding  soil  is  dry. 

REFERENCES 

1.  BEMMELN,  J.   M.   VON.    On   the   Plasticity  of   Clay  Soils.     Chem. 

Weekbl.  7  (1910),  pp.  793-805. 

2.  BREAZEALE,  J.  F.     Formation  of  Black  Alkali  (Sodium  Carbonate) 

in  Calcareous  Soils.    Jour.  Agr.  Rsch.  10  (1917),  pp.  541-589. 


REFERENCES  131 

3.  BRIGGS,  L.  J.     Salts  as  Influencing  the  Rate  of  Evaporation  of  water 

from  Soils.       U.  S.  D.  A.  Bur.  of  Soils,  Rpt.  64  (1899),  pp.  184-198. 

4.  BRIGGS,  L.  J.,  and  LAPHAM,  M.  H.     Influence  of  Dissolved  Salts  on 

the  Capillary  Rise  of  Soil  Water.     U.  S.  D.  A.  Bur.  Soils,  Bui.  19 
(1902),  18  pp. 

5.  CAMERON,  F.  K.     Application  of  the  Theory  of  Solution  to  the  Study 

of  Soils.     U.  S.  D.  A.  Bur.  Soils,  Rpt.  64  (1899^,  pp.  141-172. 

6.  DAVIS,  R.  O.  E.    The  Effect  of  Soluble  Salts  on  the  Physical  Properties 

of  Soils.     U.  S.  D.  A.  Bur.  Soils,  Bui.  82  (1911),  38  pp. 

7.  FREE,  E.  E.    The  Phenomena  of  Flocculation  and  Deflocculation. 

Jour.  Franklin  Inst.  169  (1910),  pp.  421-438,  and  170  (1911),  pp.  46- 

57- 

8.  GARDNER,  F.  D.,  and  STEWART,  JOHN.    A  Soil  Survey  of  Salt  Lake 

Valley,  Utah.     U.  S.  D.  A.  Bur.  of  Soils,  Rpt.  64  (1899),  pp.  77-114. 

9.  GEDROITS,  K.  K.     Colloid  Chemistry  in  the  Study  of  Soils.     Zhur. 

Opytn.  Agron.  (Russ.  Jour.  Exp.  Landw.),  13  (1912),  pp.  363-420. 

(Abs.  E.  S.  R.  28,  p.  516.) 
10.  HALL,  A.  D.     Some  Secondary  Action  of  Manures  upon  the   Soil, 

Jour.  Roy.  Agr.  Soc.  (England),  70  (1909), pp.  12-35.     (Abs.  E.  S.  R. 

23,  p.  320.) 
IT.   HARRIS,  F.  S.,  and  ROBINSON,  J.  S.     Factors  affecting  the  Evaporation 

of  Moisture  from  the  Soil.     Jour.  Agr.  Rsch.  7  (1916),  pp.  439-461. 

12.  HEILEMAN,  W.  H.     Alkali  and  Alkali  Soils.     Wash.  Sta.  Bui.  49  (1901), 

35  PP. 

13.  HILGARD,  E.  W.     Soils,  pp.  183-187.     (New  York,  1906.) 

14.  KELLERMAN,  K.  F.    The  Relation  of  Colloidal  Silica  to  Certain  Im- 

permeable Soils.     Sci.  n.  ser.  33  (1911),  pp.  189-190. 

15.  LOUGHRIDGE,  R.  H.     Investigations  in  Soil  Physics.     Cal.  Sta.  Rpt. 

1893-94,  pp.  70-100. 

16.  MASONI,  G.    The  Flocculating  Power  of  Some  Soluble  Salts  on  Clay 

Substances  of  the  Soil.     Spaz.  Sper.  Agr.  Ital.  45  (1912),  pp.  113- 
159.     (Abs.  E.  S.  R.  27,  p.  620.) 

17.  SACCHASE,  R.,  and  BECKER,  A.    The  Influence  of  Lime  and  Salts,  as 

well  as  Certain  Acids,  on  the  Flocculation  of  Clay.     Landw.  vers. 
Stat,  43  (1893),  PP-  15-25-     (Abs.  E.  S.  R.  5,  p.  696.) 

18.  SHARP,  L.  T.     Fundamental  Relationships  between  Certain  Soluble 

Salts  and  Soil  Colloids.     Univ.  Cal.  Pub.  Agr.  Sci.  i  (1916),  No.  10, 
pp.  291-339;  also  see  Proc.  Nat.  Acad.  Sci.  i  (1913),  pp.  563-568. 


CHAPTER  X 

RELATION  OF  ALKALI  TO  BIOLOGICAL 
CONDITIONS   IN  THE   SOIL 

THE  effect  of  soil  alkali  in  reducing  the  growth  of  crops 
or  in  changing  completely  the  type  of  native  vegetation  is 
easily  recognized.  There  are,  however,  equally  as  im- 
portant changes  produced  in  the  microorganisms.  These 
changes  cannot  be  detected  without  special  study  of  a 
technical  nature  and  are  therefore  not  so  well  understood. 
The  micro-flora  of  the  soil  is  probably  as  varied  and  as 
complex  as  the  plant  growth  on  the  surface,  but  the  re- 
sponse of  these  smaller  organisms  has  not  been  as  thoroughly 
studied  as  that  of  the  higher  plants.  However,  a  few 
rather  definite  facts  have  been  established. 

Relation  of  Soil  Organisms  to  Fertility.  —  It  has  long 
been  known  that  bacteria  and  fungi  in  the  soil  are  essential 
to  continued  growth  of  the  higher  plants.  The  constant 
tearing  down  of  dead  organic  matter  furnishes  new  material 
for  assimilation  by  living  plants.  Most  plants  require 
nitrogen  in  the  form  of  either  ammonium  salts  or  nitrate 
nitrogen.  One  of  the  important  sources  of  such  salts  is 
vegetable  matter  of  the  soil  which  has  been  reduced  to 
the  proper  form  by  decomposition.  Certain  microorgan- 
isms attack  and  break  up  the  complex  organic  tissues  of 
plants  as  soon  as  their  resistance  has  been  decreased  by 
death  or  otherwise.  Different  organisms  act  on  the  dif- 
ferent compounds  as  decomposition  proceeds  until  the 
material  is  finally  reduced  to  the  simple  compounds  such 

132 


SOIL   STERILITY  133 

as  are  required  by  plants.  Fungi  and  putrefying  bacteria 
reduce  the  vegetable  proteins  to  a  form  which  can  be  acted 
upon  by  the  ammonifying  bacteria  which  finally  leave  the 
nitrogen  in  the  form  of  ammonia;  it  may  then  be  either 
combined  into  an  ammonium  salt  and  utilized  by  the 
plant  or  oxidized  by  other  organisms  into  nitrous,  and 
then  nitric,  acid.  The  latter  combines  with  bases  in  the 
soil  to  form  nitrates.  Where  the  proper  organisms  are 
in  the  soil  in  sufficient  numbers  to  carry  this  process 
smoothly  to  a  finish  the  soil  is  usually  highly  productive. 

Desirable  organisms  other  than  of  the  class  mentioned 
above  are  the  symbiotic  nitrogen-fixing  bacteria  which 
live  in  the  nodules  of  legume  roots  and  synthesize  at- 
mospheric nitrogen  into  forms  which  can  be  utilized  by 
the  host  plant.  A  number  of  different  kinds  of  bacteria 
fix  atmospheric  nitrogen  without  symbiosis  with  higher 
plants;  still  other  organisms  are  known  to  break  up  and 
make  available  certain  insoluble  compounds  in  the  soil 
which  are  essential  to  profitable  crop  production. 

The  desirable  microorganisms  do  best  under  practically 
the  same  soil  conditions  as  do  crop  plants.  They  thrive 
or  grow  most  luxuriantly  in  soils  rich  in  organic  matter, 
well  aerated,  and  with  about  the  optimum  moisture  content 
for  most  crops.  Where  the  soil  is  water-logged,  puddled, 
or  contains  injurious  matter,  the  more  desirable  nitrify- 
ing and  nitrogen-fixing  bacteria  are  largely  replaced  by 
denitrifying  and  putrefying  organisms  which  rapidly 
deplete  the  soil  of  available  nitrogen. 

Biological  Inactivity  and  Soil  Sterility.  —  Alkali  salts 
which  injure  or  prevent  the  production  of  crops  on  certain 
lands  also  injure  the  activities  of  the  desirable  soil  organ- 
isms. Taylor  (18)  found  that  at  least  part  of  the  sterility 
of  certain  Bengal  soils  was  due  to  scarcity  of  bacteria  and 


134    BIOLOGICAL  CONDITIONS  OF  THE   SOIL 

nitrogen.  Some  soil  students  go  so  far  as  to  say  that  an 
important  part  of  the  injury  to  crop  production  on  alkali 
lands  is  due  to  decreased  bacterial  activity.  They  hold 
that  this  is  shown  by  the  fact  that  crop  yields  do  not 
always  decrease  to  the  full  extent  when  alkali  is  first  brought 
in  contact  with  the  soil,  but  continue  to  decrease  as  time 
allows  the  microorganisms  to  die  gradually.  They  also 
point  out  that  soils  do  not  become  at  once  productive  after 
being  drained  of  alkali,  but  gradually  increase  in  productive- 
ness as  the  desirable  organisms  are  given  time  to  multiply. 
Whether  the  changes  which  soils  undergo  subsequent  to 
drainage  are  due  largely  to  bacterial  activities  or  almost 
wholly  to  physiological  changes  is  not  at  present  known. 

From  preliminary  experiments  by  Lipman  and 
Fowler  (13)  in  which  soils  were  treated  with  500  parts  per 
million  of  sodium  carbonate,  1000  parts  per  million  of 
sodium  chloride,  2500  parts  per  million  of  sodium  sulphate 
and  mixed  salts,  and  then  leached  free  of  the  salts,  it  was 
found  that  nitrification  was  affected  profoundly  by  the 
leaching.  The  characteristic  effects  of  the  salts  on  the 
organisms  remained  after  the  salts  had  been  almost  en- 
tirely leached  out.  The  soil  receiving  the  mixed  salts 
was  most  toxic,  with  sodium  carbonate,  sodium  chloride, 
and  sodium  sulphate  in  the  order  named.  This  same  action 
was  noted  for  the  nitrogen-fixing  bacteria,  although  it 
was  not  so  characteristic  as  with  the  nitrifying  ones.  The 
results  with  the  ammonifiers  was  not  so  distinctive. 

Barnes  and  AH  (i)  found  that  the  ammonifying  bac- 
teria, and  to  a  less  extent  the  nitrifiers,  might  be  used  to 
measure  the  toxicity  of  the  alkali  or  its  crop-producing 
power  much  more  quickly  and  at  less  expense  than  by 
growing  crops.  They  believe  that  the  alkali  merely  causes 
the  organism  to  lie  dormant  until  favorable  conditions 


LIMITS    OF   TOXICITY  135 

again  prevail.  By  determining  the  ammonifying,  nitrify- 
ing, and  nitrogen-fixing  power  of  the  organisms  they  pro- 
pose to  classify  land  that  is  being  drained  as  to  its  ability 
to  grow  crops. 

Concentrations  of  Alkali  which  Limit  Biological  Ac- 
tivities. —  The  quantity  of  alkali  that  Will  cause  injury 
to  the  ammonifying  and  nitrifying  bacteria  as  determined 
by  different  investigators  varies  from  a  minimum  of  250 
parts  per  million  of  sodium  carbonate,  which  was  found 
by  Lipman  (10)  to  inhibit  growth  of  these  organisms,  to 
a  maximum  of  4000  parts  per  million  of  this  salt  as  found 
by  Kelley  (8) .  The  nature  and  concentration  of  the  nitrog- 
enous material  used  to  determine  the  activity  of  the  or- 
ganisms has  been  found  to  make  a  great  difference  in  the 
rate  of  nitrification.  Kelley  found  that  where  i  per 
cent  of  dried  blood  was  used  as  the  nitrogenous  material, 
500  parts  per  million  of  sodium  carbonate  was  distinctly 
toxic,  but  where  only  o.i  per  cent  of  dried  blood  was  used 
the  organisms  were  apparently  not  affected  by  the  presence 
of  4000  parts  per  million  of  sodium  carbonate.  He  also 
found  that  while  1000  parts  per  million  of  sodium  car- 
bonate were  toxic  to  nitrification  in  the  presence  of  0.15 
per  cent  of  ammonium  sulphate,  this  concentration  was 
markedly  stimulating  in  the  presence  of  0.0625  per  cent  of 
ammonium  sulphate.  The  large  discrepancies  in  the 
quantities  of  alkali  which  these  bacteria  withstand  are 
probably  due  in  part  to  the  differing  quantities  and  kinds 
of  nitrifying  materials  used  as  well  as  the  kind  and  dif- 
fering natures  of  the  soils.  Dried  blood,  cottonseed  meal, 
ammonium  sulphate,  and  numerous  other  materials  have 
been  used;  this  makes  comparisons  of  the  different  ex- 
periments difficult.  Standard  methods  are  needed  in  this 
regard  as  they  are  in  other  alkali  work.  It  is  probable 


136      BIOLOGICAL  CONDITIONS  OF  THE   SOIL 

that  absorption  of  the  sodium  carbonate  by  the  organic 
matter  of  the  soil  plays  a  considerable  part  in  these  ex- 
periments, as  the  salts  were  added  to  the  soil,  and,  as 
mentioned  in  Chapter  V,  loam  soils,  especially  those  high 
in  organic  matter,  do  not  hold  in  solution  all  of  the  sodium 
carbonate  added. 

The  various  experiments  agree  pretty  well  that  about 
1000  parts  per  million  of  sodium  chloride  is  a  toxic  quantity. 
Greaves,  Carter,  and  Goldthorpe  (6)  found  a  stimulation 
with  this  salt  up  to  a  concentration  of  about  1000  parts 
per  million  above  which  there  was  a  marked  toxicity 
Other  investigators  have  found  stimulation  where  the 
quantities  of  sodium  chloride  were  lower  than  this. 

From  the  available  experiments,  the  toxic  limits  of 
sodium  sulphate  appear  to  lie  between  2500  and  5000 
parts  per  million.  Small  quantities  of  this  salt  were  found 
to  be  stimulating  to  nitrifying  bacteria  by  Brown  and 
Hitchcock  (2),  but  Greaves  and  his  associates  (6)  found 
no  stimulation  even  in  soils  containing  very  small  quanti- 
ties of  sodium  sulphate. 

Greaves  found  the  toxic  limits  for  sodium  nitrate  to  be 
only  a  little  greater  than  200  parts  per  million,  or  much 
more  toxic  in  comparison  with  its  toxicity  to  wheat  than 
are  the  other  sodium  salts.  The  quantities  of  sodium 
carbonate,  sodium  chloride,  and  sodium  sulphate  present 
in  soils  producing  half  the  quantity  of  dry  matter  of  normal 
wheat  plants  and  those  in  soils  producing  half-normal 
nitrification  were  found  to  be  nearly  the  same.  The 
salts  which  stimulated  wheat  most  also  stimulated  nitri- 
fying bacteria. 

From  the  low  quantities  of  sodium  carbonate  and  sodium 
nitrate  which  cause  injury  to  nitrifying  bacteria,  it  appears 
that  the  puddling  effect  of  these  salts  may  play  an  im- 


LIMITS    OF    TOXICITY  137 

portant  part  in  their  toxicity.  In  Colorado  (17),  however, 
soils  containing  rather  large  quantities  of  nitrates  were 
found  to  be  still  active  in  nitrifying,  although  when  the 
nitrates  became  excessive  the  organisms  were  destroyed 
or  greatly  checked  in  their  activity. 

Kelley  (8)  found  that  the  nitrite-forming  organisms 
were  still  active  in  soil  containing  so  much  alkali  that 
nitrate  formation  had  practically  ceased. 

Nitrogen-fixing  organisms  were  found  by  Lipman  and 
Sharp  (14)  to  be  inhibited  by  the  presence  of  4000  to  5000 
parts  per  million  of  sodium  carbonate.  The  toxic  limits 
for  sodium  chloride  were  5000  to  6000  parts  per  million, 
and  for  sulphate  about  12,500  parts  per  million.  Much 
smaller  quantities  were  found  injurious  where  the  soil  was 
leached  of  its  salts,  the  quantity  in  this  experiment  being 
nearly  the  same  as  with  the  nitrifying  bacteria  (13). 

Hills  (7)  reports  that  1500  parts  per  million  of  sodium 
nitrate  stopped  multiplication  and  probably  killed  many  of 
the  nitrogen-assimilating  organisms.  Symbiotic  bac- 
teria (15)  on  peas  were  retarded  in  their  activities  when 
sodium  salts  in  cultural  solutions  with  a  strength  of  3333 
parts  per  million  were  used.  Alkaline  nitrates  at  a  con- 
centration of  100  parts  per  million  and  ammonium  salts 
at  a  concentration  of  500  parts  per  million  checked  the 
production  of  root  tubercles. 

Ammonification  organisms  have  been  found  by  investi- 
gators who  have  experimented  with  them  in  comparison 
with  those  concerned  with  nitrification  and  nitrogen- 
fixation  to  be  more  tolerant  of  alkali  than  these  other 
nitrogen-working  organisms.  Lipman  found  the  toxic 
points  for  ammonification  to  be  at  20,000  parts  per 
million  of  sodium  carbonate,  1000  to  2000  parts  per 
million  of  sodium  chloride,  and  4000  parts  per  million 


138     BIOLOGICAL  CONDITIONS  OF  THE  SOIL 

of  sodium  sulphate.  For  one-half  normal  ammonifying 
power,  Greaves  found  the  points  to  be  at  n,6'6o  .parts 
per  million  of  sodium  carbonate,  1170  parts  per  million  of 
sodium  chloride,  and  8520  parts  per  million  of  sodium 
sulphate.  The  results  of  Brown  and  Johnson  (3)  indicate 
a  lower  limit,  but  all  show  that  sodium  chloride  is  the  most 
toxic.  The  relationship  of  the  three  salts  is  nearly  re- 
versed to  that  in  their  action  on  plants.  Greaves  (5)  found 
sodium  nitrate  to  be  toxic  at  about  426  parts  per  million. 
He  noticed  a  stimulating  effect  of  sodium  carbonate, 
sodium  nitrate,  and  sodium  chloride  in  decreasing  order 
when  only  small  quantities  of  these  salts  were  present, 
but  found  none  with  sodium  sulphate.  His  experiment 
also  showed  that  some  salts  increase  in  toxicity  with  in- 
creasing quantities  of  salts  much  faster  than  others. 

Lipman  (9)  noticed  antagonism  between  the  anions  of 
the  sodium  salts,  the  action  being  strongest  between  7000 
parts  per  million  sodium  carbonate  and  2000  parts  per 
million  sodium  chloride,  next  between  sodium  carbonate 
and  sodium  sulphate,  and  weakest  between  sodium  chlo- 
ride and  sodium  sulphate.  Antagonism  was  noted  "be- 
tween toxic  and  stimulating  salts  as  well  as  between  two 
toxic  salts."  A  reduction  of  the  stimulating  effect  of 
sodium  carbonate  on  ammonification  was  noticed  by 
Brown  and  Johnson  (3)  when  calcium  carbonate  was  added 
to  the  soil,  but  the  toxic  effect  was  also  reduced.  Both 
sodium  chloride  and  sodium  sulphate  showed  more  stimu- 
lation and  certain  toxic  quantities  became  stimulating 
when  calcium  carbonate  was  added.  "  Combinations  of 
various  salts  in  non-toxic  individual  amounts  in  the  pres- 
ence of  calcium  carbonate  became  toxic  to  ammonification." 

Other  soil  organisms  have  been  little  studied.  Mun- 
ter's  (16)  experiments  show  that  Actinomycetes  were 


REFERENCES  139 

stimulated  by  the  addition  of  50,000  parts  per  million  of 
potassium  chloride  or  sodium  chloride,  but  that  spore 
formation  was  decreased,  while  100,000  parts  per  million 
usually  arrested  development. 


REFERENCES 

1.  BARNES,  J.  H.,  and  ALT,  BARKAT.     Alkali  Soils:    Some  Biochemical 

Factors  in  their  Reclamation.     Agr.  Jour.  India,  12  (1917),  pp.  368- 
389.     (Abs.  E.  S.  R.  38,  p.  815.) 

2.  BROWN,  P.  E.,  and  HITCHCOCK,  E.  B.     The  Effects  of  Alkali  Salts  on 

Nitrification.     Soil  Sci.  4  (1917),  pp.  207-229. 

3.  BROWN,  P.  E.,  and  JOHNSON,  D.  R.     Effects  of  Certain  Alkali  Salts 

on  Nitrification.     Iowa  Sta.  Res.  Bui.  44  (1918),  24  pp. 

4.  GREAVES,  J.  E.     Azofication.     Soil  Sci.  6  (1918),  pp.  163-217. 

5.  Greaves,  J.  E.     The  Influence  of  Salts  on  the  Bacterial  Activities  of 

the  Soil.     Soil  Sci.  2  (1916),  pp.  443-480. 

6.  GREAVES,  J.  E.,  CARTER,  E.  G.,  and  GOLDTHORPE,  H.  C.     Influence 

of    Salts  on  the  Nitric-nitrogen  Assimilation.     Jour.  Agr.  Res.  16 
(1919),  pp.   107-135. 

7.  HILLS,  T.  L.     Influence  of  Nitrates  on  Nitrogen  Assimilation.    Jour. 

Agr.  Res.  12  (1918),  pp.  183-230. 

8.  KELLEY,  W.  P.     Nitrification  in  Semiarid   Soils.     Jour.  Agr.  Res.  7 

(1916),  pp.  417-437. 

9.  LIPMAN,  C.  B.     Antagonism  between  Anions  as  Affecting  Ammoni- 

fication  in  Soils.      Centbl.  f.  Bakt.  Abt.  2,  Bd.  36  (1913),  pp.  382- 
394- 

10.  LIPMAN,  C.  B.     Toxic  Effects  of  Alkali  Salts  in  Soils  on  Soil  Bacteria. 

II.     Nitrification.      Centbl.    i.     Bakt.    Abt.    2,    Bd.    33      (1912), 
PP-  3°5-3i3- 

11.  LIPMAN,  C.  B.    Toxic  Effects  of  Alkali  Salts  on  Soil  Bacteria.     I.  Am- 

monification.     Centbl.  f.  Bakt.  Abt.  2,  Bd.  32  (1911),  pp.  58-64. 

12.  LIPMAN,  C.  B.,  BURGESS,  P.  S.,  and  KLEIN,  M.  A.     Comparison  of  the 

Nitrifying  Powers  of  Some  Humid  and  Some  Arid  Soils.     Jour. 
Agr.  Res.  7  (1916),  pp.  47-82. 

13.  LIPMAN,  C.  B.,  and  FOWLER,  T.  W.     Preliminary  Experiments  of  Some 

Effects  of  Leaching  on  Soil  Flora.     Soil  Sci.  i  (1916),  pp.  291-297. 

14.  LIPMAN,  C.  B.,  and  SHARP,  L.  T.    Toxic  Effects  of  Alkali  Salts  in  Soils 

on  Soil  Bacteria.    III.     Nitrogen  Fixation.     Centbl.  f.  Bakt.  Abt. 
2,  Bd.  35  (1912),  pp.  647-655. 


140      BIOLOGICAL   CONDITIONS  OF  THE   SOIL 

15.  MARCHAL,  E.     Influence  of  Mineral  Salts  on  the  Production  of  Tuber- 

cles on  Pea  Roots.     Compt.  Rend.  Acad.  Sci.  (Paris),. 133  (1901), 
pp.  1032-1033.     (Abs.  E.  S.  R.  13,  p.  1017.) 

16.  MUNTER,  E.     The  Influence  of  Inorganic  Salts  on  the  Development  of 

Actinomycetes,  III.       Centbl.  f.  Bakt.  2  Abt.  Bd.  44  (1916).  pp.  673- 

695. 

17.  SACKETT,  W.  G.     Bacteriological  Studies  pf  the  Fixation  of  the  Nitro- 

gen in  Certain  Colorado  Soils.     Colo.  Sta.  Bui.  179  (1911). 

18.  TAYLOR,  C.  S.     Effect  of  Salts  on  Soils.     Dept.  Agr.  (Bengal),  Quart. 

Jour.  2  (1909),  pp.  281-287.     (Abs.  E.  S.  R.  22,  p.  124.) 


CHAPTER  XI 

MOVEMENT  OF   SOLUBLE   SALTS  THROUGH 
THE   SOIL 

THE  greatest  problem  connected  with  the  utilization  of 
alkali  lands  is  control  of  the  movement  of  soluble  salts. 
Were  it  possible  to  handle  the  land  economically  so  that 
the  movement  of  the  alkali  would  be  continually  down- 
ward into  the  subsoil,  or  better,  into  the  drainage  system 
where  it  would  be  permanently  removed  from  the  feeding 
zone  of  the  plants,  the  alkali  problem  would  be  solved. 
The  upward  translocation  of  enormous  quantities  of 
soluble  salts  into  the  top  foot  or  two  of  soil  has  ruined 
vast  areas  of  the  most  productive  lands  of  the  arid  regions. 

Salts  in  Natural  Soils.  —  Where  undisturbed  by  flooding 
and  where  the  water-table  is  a  cpnsiderable  distance  be- 
low the  surface,  soluble  salts  tend  to  accumulate  at  some 
distance  beneath,  rather  than  at  the  surface  of  arid  soils. 
The  rainfall  is  light  and  frequently  so  distributed  that  the 
moisture  penetrates  to  a  distance  of  only  3  to  4  feet 
in  most  soils.  Much  of  the  water  that  enters  the  soil 
is  needed  by  the  plants  growing  upon  it  and  this  water  is 
extracted  some  distance  below  the  surface.  A  large  part 
of  the  movement  of  salts  is  in  connection  with  capillary 
action,  and  because  the  capillary  movement  of  moisture 
to  the  surface  of  the  soil  is  reduced  by  the  rapid  drying 
out  of  the  surface  soil,  little  of  the  water  is  allowed  to 
evaporate  at  the  surface  and  deposit  its  soluble  salts. 
Since  there  is  little  movement  of  water  except  through 

141 


142  MOVEMENT   OF    SOLUBLE   SALTS 

roots  in  deep  arid  soils,  and  since  the  first  flush  of  water 
passing  through  a  soil  usually  carries  considerably  more 
salts  than  the  subsequent  water,  the  usual  movement  of 
alkali  under  natural  conditions  is  toward  the  lower  point 
of  rain  penetration.  In  sandy  soils  or  in  regions  where 
the  rainfall  is  greater,  the  penetration  of  the  water  is 
greater  than  on  the  more  impervious  soils  or  where  the 
rainfall  is  light,  and  the  accumulation  of  the  salts  at  dif- 
ferent depths  varies  accordingly.  It  was  found  in  Cali- 
fornia (16)  that  on  a  sandy  loam  soil  with  a  rainfall  of  8 
inches  the  greatest  accumulation  of  salts  was  at  a  depth  of 
3  to  4  feet,  whereas  in  a  coarse  sandy  soil  in  the  same  place 
the  depth  of  greatest  salts  was  below  4  feet.  Where  the 
rainfall  was  only  3  inches  the  maximum  salt  was  at  about 
18  inches  in  a  sandy  loam  soil,  whereas  with  15  inches  the 
bulk  of  the  salts  was  at  5  feet. 

Salt  Movement  with  Water.  —  When  these  arid  lands 
are  brought  under  irrigation,  however,  this  balanced  con- 
dition is  frequently  upset.  The  soil  is  kept  so  much 
more  moist  that  capillary  action  is  much  easier,  and  not 
infrequently  seepage  and  over-irrigation  raise  the  water- 
table  so  high  that  upward  movement  is  possible  from  the 
free  water  in  the  soil.  Under  such  conditions,  the  alkali 
accumulations  of  the  lower  depths  are  moved  to  the  upper 
zone  of  soil  where  they  become  of  greatest  injury  to  plants. 
It  is  in  this  manner  that  many  of  the  formerly  productive 
irrigated  lands  have  been  rendered  useless. 

Diffusion  of  the  salts  in  the  soil  plays  a  local  part  in  the 
movement  of  alkali,  but,  according  to  the  laboratory 
work  of  McCool  and  Millar  (23)  and  others,  diffusion 
causes  changes  for  only  a  few  inches  about  concentrated 
salt  solutions,  and  the  field  observations  of  Mackie  (24), 
Headden  (14),  Hansen  (7),  and  others  show  that  because 


SALT   MOVEMENT   WITH  WATER 


143 


of  the  differences  in  the  character  and  concentration  of 
alkali  in  short  distances  vertically  or  horizontally,  there 
must  be  movement  of  water  before  significant  movements 
of  salts  are  possible. 

The  extent  to   which   salts  move  with  water  passing 
through  a  soil  has  been  studied  by  a  number  of  investi- 


FIG.  17.  —  CULTIVATED  LAND  THAT  HAD  TO  BE  ABANDONED 
BECAUSE  OF  THE  RlSE  OF  ALKALI. 

gators.  In  laboratory  experiments,  with  alkali  soils  kept 
so  continually  moist  that  there  was  constant  water  move- 
ment, the  author  (9)  has  shown  that  alkali,  principally 
sodium  chloride,  is  very  readily  transported  from  one  por- 
tion of.  the  soil  to  another,  either  upward  or  horizontally. 
The  salts  became  very  concentrated  in  the  upper  inch  or 
two  of  soil  where  the  water  was  allowed  to  evaporate, 
The  first  water  percolating  through  alkali  soil  contained 
several  times  as  much  salts  as  was  found  later.  Tulay- 
kov  (30)  found  salts  moved  gradually  and  more  or  less 


144  MOVEMENT   OF    SOLUBLE   SALTS 

completely  to  the  surface  of  a  column  of  soil  150  cm.  in 
height  supplied  with  water  at  the  bottom.  Hilgard  as 
well  as  Puchner  (28)  and  others  have  noted  a  migration 
of  salts  upward  and  downward  as  the  moisture  changed 
places. 

The  latter  experimenter,  using  quartz  sand,  loam, 
and  rich  humus  soils,  found  the  movement  to  depend 
somewhat  on  the  chemical  and  physical  properties  of  the 
soils.  Powdery  soils  allowed  the  salts  to  move  more 
readily  than  crumbly  soils.  Kossovich  (20)  reports  a 
greater  movement  on  a  loess  clayey  soil  than  on  a  sandy 
soil  and  that  sodium  chloride  hastened  the  rise  of  water 
while  sodium  carbonate  impeded  it.  It  is  probable  that 
the  differences  both  in  nature  of  the  salts  and  their  con- 
centration so  often  noticed  in  fields  containing  alkali  are, 
in  part  at  least,  due  to  changes  in  the  nature  of  the  soils 
which  in  turn  modify  the  rate  of  capillary  action.  In 
studies  of  the  movement  of  moisture,  Briggs  and  Lapham  (2) 
conclude  that  "concentrated  or  saturated  solutions  of  all 
salts  materially  diminish  capillary  action,"  but  that  in 
dilute  solutions  the  neutral  salts  had  very  little  influence 
on  capillary  action.  They  found  sodium  carbonate  to  have 
a  greater  influence  on  capillarity  than  the  neutral  salts. 

The  extent  of  the  fluctuation  of  salts  upward  and  down- 
ward under  irrigation  in  the  field  has  not  been  determined 
with  any  degree  of  accuracy.  Hilgard  considered  the 
movement  to  be  mostly  in  the  top  four  feet.  Considering 
the  ease  with  which  the  salts  move  with  the  water  and 
from  observations  of  the  movement  of  soluble  salts  with 
irrigation  water  when  no  alkali  was  present  (n),  it  is  very 
probable  that  the  salts  are  frequently  moved  to  great 
depths  where  not  prevented  by  impervious  soils  or  by  a 
water-table.  Investigations  show  that  water  is  seldom 


EFFECT  OF   WATER-TABLE  145 

drawn  to  the  surface  by  capillary  action  from  a  depth 
greater- than  2  or  3  feet,  so  that  the  greater  part  of  the  alkali 
which  penetrates  beyond  this  depth  never  again  reappears 
at  the  surface  unless  the  water-table  rises  to  within  a  few 
feet  of  the  surface.  Water  movement  below  the  top  2  or 
3  feet  is  probably  caused  by  moisture  removed  by  the  plants 
or  by  the  action  of  gravity  so  that  it  is  improbable  that 
there  is  such  movement  of  salts  other  than  local  diffusion 
and  movement  with  the  gravitational,  or  free,  water. 

Effect  of  Water-table.  —  Where  the  drainage  is  poor 
so  that  there  is  a  rise  of  the  water-table  the  conditions  are 
modified  accordingly.  With  a  water-table  near  the  sur- 
face, the  soluble  salts  dissolved  from  the  soil  by  down- 
ward movement  are  held  where  they  may  be  drawn  by 
capillarity  to  the  surface  and  again  accumulate.  Head- 
den  (14)  observed  that  the  water  in  shallow  wells  rose  in 
salt  content  from  2871  parts  per  million  before  an  irriga- 
tion to  4444  parts  per  million  twelve  days  following  and 
then  gradually  fell  to  2590  parts  per  million  just  before  the 
next  irrigation. 

He  and  also  Mackie  (24)  noticed  that  the  concentra- 
tion of  the  top  of  the  water-table  was  greater  than  the 
lower  depths  and  that  there  was  a  rather  gradual  de- 
cline in  the  soluble  salts  in  the  water  with  depth.  As 
the  water-table  rises  the  most  concentrated  solutions  are 
presented  for  upward  translocation.  Headden  (14)  made 
a  rather  detailed  study  of  the  effect  of  seasonal  movement 
of  water-tables  from  which  he  concluded  that  as  the  water 
fell  much  of  the  salts  in  the  free  water  was  retained  by  the 
soil  so  that  the  free  water  gradually  became  weaker  as  it 
sank  and  again  increased  as  it  rose.  He  (15)  found  that 
the  kind  and  quantity  of  salts  in  the  soil  solution  differed 
markedly  from  those  found  in  the  free  ground  water  or 


146  MOVEMENT    OF    SOLUBLE   SALTS 

from  the  alkali  incrustations  on  top  of  alkali  soil.  Certain 
of  the  soluble  salts  were  absorbed  by  the  soil,  while  others 
moved  somewhat  more  freely.  Calcium  sulphate  was  the 
most  abundant  salt  in  the  soil  solution  with  magnesium 
sulphate  second,  while  sodium  sulphate  formed  consider- 
able of  the  efflorescent  matter  on  the  surface,  and  the 
salts  next  the  surface.  Sodium  chloride  did  not  separate 
as  readily  as  some  of  the  other  salts.  Very  little  calcium 
sulphate  left  the  soil  to  form  part  of  the  incrustation. 

Movement  of  Various  Salts.  —  It  has  been  noticed  by 
numerous  observers  that  the  different  salts  move  some- 
what independent  of  each  other  so  that  in  comparatively 
short  distances  either  vertically  or  horizontally  rather 
marked  differences  are  found.  Experimenters  have  come 
to  varying  conclusions  as  to  the  ease  of  movement  of  the 
different  alkali  salts.  Practically  all  field  investigations 
have  shown  that  the  chlorides  are  the  most  sensitive  to 
water  movement.  Both  under  arid  alkali  soils  and  where 
irrigation  has  shifted  the  salts  to  other  positions,  sodium 
chloride  is  generally  found  in  its  highest  concentration  at 
the  point  where  the  total  salts  are  highest.  Headden  (12, 
13)  states  that  while  retention  of  salts  differs  with  the  soil, 
sodium  sulphate  was  most  markedly  retained,  sodium 
chloride  slightly,  and  sodium  carbonate  hardly  at  all, 
and  that  " there  is  a  tendency  for  the  'white  alkali'  to 
pass  into  the  deeper  seated  waters"  and  out  of  the  region 
where  there  is  good  drainage.  King  (18)  reports  sodium 
sulphate  as  being  readily  absorbed  by  the  soil,  while 
sodium  chloride  was  not  retained.  The  soil  has  a  slight 
retentive  power  for  the  acid  radical  of  sulphates  but  none 
for  nitrates,  chlorides,  nor  carbonates  according  to  Waring- 
ton  (32).  Dimo  (4)  noticed  accumulations  of  sodium 
chloride  and  sodium  sulphate  at  a  depth  of  50  cm.  in  a 


MOVEMENT  OF  VARIOUS   SALTS  147 

field  soil,  while  in  the  deeper  layers  sodium  bicarbonate 
and  sodium  carbonate  gradually  replaced  the  former  salts. 
The  work  of  Mackie  (24)  in  California  indicated  that 
sodium  carbonate  was  readily  absoibed  by  the  soils  and 
therefore  held  its  position  in  the  soil  well.  On  irrigated 
soils  he  usually  found  sodium  carbonate'  in  the  greatest 
quantities  near  the  surface,  but  on  virgin  soil  its  location 
varied  in  depth  down  to  the  hardpan.  From  results  on 

/   '  '        :.&  • 


FIG.  18. — ALKALI  EATING  AWAY  THE  FENCE  POSTS. 

land  irrigated  4  or  5  years  presented  by  Hilgard  and 
Loughridge  (16)  it  appears  that  sodium  chloride  moved 
upward  to  the  first  foot  relatively  faster  than  sodium  sul- 
phate and  considerably  faster  than  sodium  carbonate. 

Few  data  are  at  hand  to  show  to  what  extent  this  dif- 
ference in  the  rate  of  movement  of  the  different  salts  pro- 
ceeds under  field  conditions.  Analyses  of  drainage  water 
from  alkali  land  near  Salt  Lake  City,  Utah,  reported  by 
Dorsey  (6)  show  that  in  the  course  of  three  years  the 
chloride  was  removed  relatively  faster  than  the  other 
alkali  salts  when  it  constituted  by  far  the  greater  part  of 


148  MOVEMENT   OF   SOLUBLE   SALTS 

the  alkali.  Drainage  of  a  soil  in  California  (22)  removed 
about  85  per  cent  of  the  sodium  chloride,  83  per  cent  of 
the  sodium  sulphate;  drainage  and  conversion  to  sulphate 
reduced  the  sodium  carbonate  content  to  65  per  cent  of 
the  original  quantity. 

Rate  of  Alkali  Movement.  —  Theoretically,  the  alkali 
salts  are  so  soluble  that  their  removal  from  the  soil  by 
drainage  should  take  only  a  short  time,  but  in  practice  it 
often  takes  several  years  to  reduce  the  salt  content  of 
seriously  affected  alkali  lands  sufficiently  to  produce 
crops.  Dorsey  (5)  attempts  to  explain  the  difficult  move- 
ment by  the  theory  that  the  salts  from  the  descending 
free-water  solution  are  drawn  into  the  capillary  spaces 
of  the  soil  where  rapid  downward  movement  is  prevented. 
Subsequent  downward  percolation  is  attributed  to  dif- 
fusion of  the  salts  outward  into  the  free- water  spaces. 

Warington  (32)  states  that  the  first  water  percolating 
through  land  containing  soluble  salts  at  the  surface  was 
much  more  concentrated  than  subsequent  leachings  but 
that  where  the  chloride  was  first  incorporated  in  the  soil 
and  then  leached  its  concentration  in  successive  leachings 
gradually  increased.  He  explains  this  by  assuming  that 
the  first  water  that  comes  from  a  drain  passes  through 
cracks  and  burrows  of  insects  and  comes  direct  from  the 
surface,  while  that  passing  through  the  soil  spaces  alone 
does  not  arrive  until  later. 

To  explain  the  extremely  slow  movement  of  soil  solu- 
tions through  alkali  soils,  especially  those  under  laboratory 
or  other  conditions  where  the  alkali  is  added  to  the  soil  as 
a  single  salt,  Sharp  (29)  offers  the  theory  that  the  alkali 
salts  react  with  the  colloids  of  the  soil  causing  diffusion. 
He  found  that  where  solutions  of  sodium  chloride  or  sodium 
sulphate  were  in  constant  contact  with  the  soil  the  rate  of 


RATE  OF  ALKALI  MOVEMENT  149 

percolation  was  increased,  but  that  where  soils  treated 
with  these  salts  were  leached  the  rate  of  percolation  was 
diminished.  In  one  experiment  it  was  noticed  that  the 
quantity  of  suspended  matter  leached  from  soil  containing 
sodium  chloride  was  ten  times  that  from  the  check  and  that 
the  rate  of  percolation  had  been  diminished  to  about  one- 
tenth  that  of  the  check.  It  was  further  learned  that  once 
the  sodium  chloride  was  leached  from  the  soil  a  larger 
quantity  was  required  again  to  flocculate  the  soil  and  that 
it  was  more  difficult  thereafter  to  repair  the  deflocculated 
condition.  A  large  number  of  investigators  have  noted 
an  increase  of  calcium  and  magnesium  and  a  decrease  in 
sodium  in  alkali  water  after  it  had  percolated  through  a 
soil.  This  exchange  of  bases  is  said  by  Sharp  to  result 
from  displacement  of  calcium  and  magnesium  by  the 
sodium  in  the  colloidal  substances  of  the  soil  and  the  re- 
sulting increased  diffusibility  to  be  the  cause  of  the  retarded 
movement  of  the  water.  The  removal  of  the  calcium  and 
magnesium  from  the  soil  is  thought  by  him  to  be  of  less 
importance  than  the  increased  diffusibility  of  the  colloids, 
although  these  bases  are  recognized  as  being  important 
in  the  deflocculation  of  the  colloids  and  in  maintaining 
the  proper  physical  properties  of  the  soil.  Contrary  to 
Sharp's  results,  Pagnoul  (26)  did  not  find  the  sodium  of 
sodium  sulphate,  nor  to  an  appreciable  extent  sodium 
carbonate,  to  replace  lime  of  the  soil,  and  other  experi- 
menters do  not  report  sodium  sulphate  as  replacing  lime 
except  where  sodium  chloride  was  also  present.  Pagnoul 
agrees  with  Sharp  that  lime  replaces  the  bases  of  chlorides 
of  potash,  soda,  and  ammonia.  If  the  degree  of  per- 
meability to  water  can  be  taken  as  a  measure  of  the  de- 
flocculation of  soils,  experiments  by  Beeson  (i)  show 
sodium  chloride  to  be  more  than  twice  as  powerful  as 


150  MOVEMENT    OF  SOLUBLE   SALTS 

sodium  carbonate  as  a  deflocculating  agent  but  less  than 
one-half  as  powerful  as  sodium  nitrate.  Percolation  was 
at  the  rate  of  1.2  cc.  per  hour  for  soil  containing  1886  parts 
per  million  of  sodium  chloride  and  at  the.  rate  of  4.1  cc. 
per  hour  for  soil  containing  11,457  parts  per  million  of 
sodium  sulphate,  while  that  of  the  untreated  soil  was  at 
the  rate  of  10.2  cc.  per  hour.  Hare  (8),  however,  found 
sodium  chloride  much  easier  to  leach  into  the  deeper 
layers  of  the  soil  than  sodium  sulphate  and  that  the  dif- 
ference was  many  times  greater  in  an  adobe  soil  than  in 
a  sandy  loam.  It  was  with  great  difficulty  that  the  sodium 
sulphate  was  leached  downward  in  the  adobe  soil,  the 
depth  being  2  inches  for  three  six-inch  irrigations,  while 
this  amount  of  irrigation  washed  the  sodium  chloride  to 
a  depth  of  32  inches,  and  four  three-inch  irrigations  washed 
the  sodium  carbonate  to  a  depth  of  20  inches.  The  sodium 
chloride  moved  more  freely  than  the  other  two  salts  in 
both  adobe  and  sandy  loam. 

The  above  experiments  were  performed  with  pure,  salts. 
Cameron  and  Patten  (3)  found  that  when  using  black 
alkali  soils  brought  from  the  fields  and  containing  notable 
quantities  of  sodium  sulphate,  besides  the  sodium  car- 
bonate and  small  quantities  of  chlorides,  the  "  neutral 
salts  such  as  the  chlorides  in  the  presence  of  carbonates 
can  be  comparatively  readily  and  completely  leached 
from  the  soil.  With  continued  leaching  of  soils  contain- 
ing ' black  alkali'  there  is  an  increase  in  the  rate  at  which 
percolation  takes  place,  due  probably  to  the  reduction  of 
the  amount  of  alkali  present  and  its  effect  on  the  physical 
structure  of  the  soil.  Soils  containing  '  black  alkali' 
can  be  reclaimed  by  leaching,  but  the  time  and  the  amount 
of  water  required  are  probably  much  greater  than  in  the 
case  of  white  alkali." 


REFERENCES  151 

Very  little  attention  has  been  given  to  the  effect  of  the 
different  alkalies  on  the  physical  conditions  of  field  soils; 
consequently,  it  is  not  known  whether  or  not  the  rate  of 
movement  of  salts  under  field  conditions  is  checked  by 
washing  the  salts  out  of  the  soil  as  in  the  above  laboratory 
experiments.  The  last-mentioned  experiment  apparently 
indicates  that  when  the  salts  are  mixed,  as  under  field 
conditions,  the  deleterious  action  of  the  neutral  salts  is 
not  so  great  as  under  the  laboratory  mixing  conditions. 

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649. 

2.  BRIGGS,  L.  J.,  and  LAPHAM,  M.  W.     Capillary  Studies  and  Filtration 

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Arables  du  Pas-de-Calais,  Arras:    1894,  128  pp.      (Abs.  E.  S.  R.  6, 
p.  1 1 8-.) 

27.  PATTON,  H.  E.,  and  WAGGAMAN,  W.  H.    Absorption  by  Soils.    U.  S. 

D.  A.  Bur.  Soils,  Bui.  52  (1908),  95  pp. 

28.  PUCHNER,   H.     Concerning  the  Transport  of    Soluble  Salts  by   the 

Movement  of  Water  in  the  Soil.     Forsch.  Geb.  Agr.  Phys.  18  (1895), 
pp.  1-26.     (Abs.  E.  S.  R.  7,  p.  373-) 


REFERENCES  153 

29.  SHARP,  L.  T.     Fundamental  Interrelationships  between  Certain  Soluble 

Salts  and  Soil  Colloids.     Univ.  Cal.  Pub.  Agr.  Sci.  i  (1916),  pp.  291- 

339- 

30.  TULAYKOV,  N.     Some  Laboratory  Experiments  on  the  Capillarity  of 

Soils.  Russ.  Jour.  Exp.  Landw.  8  (1907),  pp.  629-666.  (Abs.  E. 
S.  R.  20,  p.  517.) 

31.  TULAYKOV,  N.,  and  KOSSOVICH,  P.    The  Soils  of, the  Muganj  Steppe 

and  Their  Transformation  into  Alkali  Lands  6y  Irrigation.  Ann. 
Inst.  Agron.  (Moscow),  12  (1906),  pp.  27-255.  (Abs.  E.  S.  R.  21, 
p.  818.) 

32.  WARTNGTON,  R.    Physical  Properties  of  Soil,  pp.  188-231.     (Oxford, 

1900.) 


CHAPTER  XII 
METHODS  OF  RECLAIMING  ALKALI  LANDS 

No  single  method  of  reclamation  is  adapted  to  all  alkali 
lands.  Many  conditions  must  be  considered  in  deciding 
what  methods  to  adopt.  The  source  of  the  alkali,  the 
texture  of  the  soil,  the  slope  of  the  land,  the  depth  of  the 
water-table,  the  price  and  supply  of  reclaiming  materials, 
the  kind  of  crops  that  will  grow  in  the  climate,  the  value 
of  the  reclaimed  land,  and  a  number  of  other  factors  must 
be  taken  into  account  before  deciding  the  advisability  of 
reclaiming  a  given  alkali  soil  and  the  methods  to  be  used 
in  case  reclamation  appears  economical.  Whatever  the 
method,  the  goal  is  the  same;  each  aims  to  check  any  in- 
creased accumulation  of  salt  and  to  reduce  the  present 
harmful  quantities  of  alkali  to  a  point  at  which  the  growth 
of  crops  will  not  be  hindered. 

The  Source  of  Contamination.  —  The  first  step  in  the 
reclamation  of  alkali  land  is  to  discover  the  source  of  the 
salt.  Intelligent  systems  of  improvement  first  discover 
and  remove  the  cause  of  the  accumulation.  As  with 
human  disease,  an  ounce  of  preventative  is  worth  a  pound 
of  cure.  Most  of  the  effort  spent  in  securing  temporary 
relief  is  wasted  if  the  trouble  soon  returns.  Work  is  done 
to  much  better  advantage  if  done  with  the  idea  of  securing 
permanent  results. 

As  pointed  out  in  Chapter  X,  alkali  comes  to  the  soil 
in  a  number  of  very  distinct  ways.  These  must  be  recog- 
nized in  deciding  which  method  of  reclamation  is  best 

154 


REDUCING  EVAPORATION  155 

adapted  to  the  conditions.  Where  an  irrigation  canal 
passes  through  a  formation  that  is  high  in  soluble  salts 
the  water  becomes  alkaline  and  carries  the  soluble  material 
to  the  land  where  the  water  is  applied.  A  canal  in  a  forma- 
tion of  this  kind  becomes  porous  when  the  salts  are  dis- 
solved. This  allows  seepage  water  to  percolate  more 
readily  from  the  canal,  increasing  the  quantity  of  water 
which  comes  out  on  land  below;  this  in  turn  causes  water- 
logging together  with  deposition  of  alkali  salts.  Lining 
the  canal  with  cement  over  the  salt-bearing  formation 
will  do  more  toward  permanent  reclamation  than  any 
number  of  temporary  devices  on  the  land  itself  which  do 
not  remove  the  source  of  the  trouble. 

Often  a  large  area  becomes  water-logged  from  a  single 
source,  and  in  arid  soils  water-logging  is  generally  fol- 
lowed by  alkali  accumulation.  A  ditch  across  the  head 
of  the  land  to  cut  off  the  water  in  cases  of  this  kind  will 
often  prevent  or  overcome  the  difficulty  without  applying 
methods  of  reclamation  on  the  land  itself. 

Some  soils  contain  a  layer  several  feet  below  the  surface 
in  which  the  salt  is  very  concentrated.  Where  this  is  the 
case,  every  effort  should  be  made  to  prevent  a  rise  of  the 
salt  to  the  surface  where  it  will  hinder  crop  growth.  If 
it  remains  at  considerable  depth,  it  may  be  entirely  harm- 
less, whereas  it  might  entirely  prevent  plant  growth  if  it 
rose  to  the  root  zone.  These  examples  show  the  relation 
of  reclamation  methods  to  the  source  of  alkali. 

Reducing  Evaporation.  —  The  chief  method  by  which 
alkali  accumulates  at  the  surface  of  the  soil  is  through 
evaporation.  The  author  (4)  has  shown  the  ease  with 
which  salts  move  with  moisture  through  the  soil.  When- 
ever water  evaporates  from  the  soil  surface  more  water  is 
moved  to  the  surface  by  capillarity  and  the  process  re- 


156 


RECLAIMING  ALKALI  LANDS 


pea  ted.     Thus,  there  may  be  a  constant  stream  from  the 
subsoil  to   the  surface,  particularly  if  the  water-table  is 


FIG.  19.  —  TYPICAL  HARD  PAN  FOUND  IN  ARID  SOILS. 

within  two  or  three  feet  of  the  surface.  All  the  water 
that  moves  transports  some  salt,  and  since  none  of  the 
salt  can  be  evaporated,  all  of  it  remains  as  a  surface  ac- 


REDUCING   EVAPORATION  157 

cumulation.  If  the  soil  is  very  low  in  soluble  salts  no 
harm  may  be  done,  but  arid  soils  usually  contain  sufficient 
salt  to  render  high  evaporation  dangerous. 

If  virgin  soil  contained  3000  parts  per  million  of  alkali, 
the  growth  of  most  crops  would  not  be  greatly  hindered; 
but  if  through  a  constant  movement  of  salt  to  the  surface 
the  salt  of  the  top  four  feet  were  concentrated  in  the  upper 
six  inches,  it  would  contain  24,000  parts  per  million,  which 
would  make  it  entirely  unsuited  to  crop  production  with- 
out reclamation.  If  evaporation  is  reduced  to  a  mini- 
mum, an  accumulation  of  this  kind  is  checked.  In  the 
reclamation  of  alkali  land  by  any  method,  it  is  desirable 
to  prevent  evaporation  as  nearly  as  possible,  because 
evaporation  causes  the  salt  to  accumulate  where  it  will 
do  most  harm. 

In  practice,  many  devices  to  reduce  evaporation  are 
employed.  These  usually  consist  of  cultivating  the  soil, 
shading  it,  or  the  establishing  of  a  good  mulch  by  adding 
manure,  straw,  leaves,  or  sand.  Of  the  various  materials 
to  be  added,  manure  is  usually  to  be  recommended  since 
it  has  sufficient  beneficial  effect  in  addition  to  the  mulch- 
ing to  pay  for  its  use,  while  others  are  of  questionable 
economic  importance. 

The  most  practical  means  of  preventing  evaporation  is 
through  cultivation.  An  unstirred  soil,  particularly  if  it 
is  heavy  —  as  many  alkali  soils  are  —  forms  a  crust 
which  acts  as  an  excellent  conductor  of  moisture.  Break- 
ing up  this  crust  by  cultivation  leaves  the  soil  loose  and 
with  but  few  points  of  connection  with  the  lower  layers 
of  soil.  As  a  result  evaporation  is  slight  even  though  the 
subsoil  remains  moist.  It  is  particularly  important  that 
the  land  be  cultivated  soon  after  irrigation  since  evapora- 
tion at  that  time  is  especially  high. 


158  RECLAIMING  ALKALI  LANDS 

Harris  and  Robinson  (5)  have  shown  that  shade  is  very 
effective  in  reducing  evaporation.  This  suggests  the 
desirability  of  keeping  alkali  land  constantly  shaded, 
preferably  by  a  crop,  which  not  only  shades  the  soil  but 
also  causes  the  water  to  pass  into  the  air  through  the 
plants  without  coming  to  the  surface.  A  growing  crop 
may  therefore  be  considered  as  one  of  the  most  important 
agencies  in  the  reclamation  of  land  containing  small 
quantities  of  alkali. 

A  water-table  near  the  surface  is  the  chief  cause  of 
harmful .  evaporation.  It  is  difficult  to  prevent  the  pas- 
sage of  large  quantities  of  water  to  the  surface  when  there 
is  an  unlimited  supply  2  or  3  feet  below.  The  prevention 
of  alkali  accumulation  calls  for  a  lowering  of  the  water- 
table  to  several  feet  from  the  surface.  The  growing  of 
green  manure  crops  instead  of  leaving  the  land  uncropped 
is  one  way  of  reducing  the  surface  accumulation  of 
alkali. 

Plowing  Under  of  Surface  Alkali.  —  Hilgard  (9)  has 
shown  at  the  Tulare  Substation,  California,  that  the  injury 
caused  by  alkali  was  reduced  by  plowing  the  surface  ac- 
cumulation under.  Part  of  a  very  bad  alkali  spot  was 
trenched  to  a  depth  of  two  feet  and  the  surface  soil  thrown 
to  the  bottom.  The  spot  thus  treated  produced  good 
wheat  crops  for  two  years,  which  was  the  time  required 
for  the  alkali  to  return  to  the  surface.  Ordinary  plowing 
is  to  some  extent  similar  to  the  above  treatment;  hence 
the  tendency  of  salts  to  accumulate  at  the  surface  by 
evaporation  of  water  is  in  part  overcome  by  ordinary 
field  practices. 

In  order  that  this  operation  may  be  effective,  the  plow- 
ing should  be  as  deep  as  possible,  since  salt  turned  under 
only  3  or  4  inches  deep  would  return  rapidly  to  the  sur- 


REMOVING  FROM  SURFACE  159 

face,  or  even  worse,  the  highest  concentration  would  be 
in  the  soil  layer  where  young  plants  were  getting  their 
start.  The  plowing  under  of  alkali  cannot  be  considered 
in  any  sense  as  getting  rid  of  it.  The  most  that  can  be 
claimed  is  that  injury  is  retarded  till  drainage  or  some  other 
permanent  means  of  elimination  begins  to  operate. 

Removing  from  Surface.  —  In  certain  cases  where  most 
of  the  salts  have  accumulated  at  the  surface,  it  is  possible 
to  remove  large  quantities  without  the  use  of  covered 
drains.  Surface  removal  is  accomplished  by  scraping  or 
sweeping  off  the  salt  or  by  dissolving  it  and  then  draining 
off  the  solution.  Scraping  and  sweeping,  in  order  to  be 
practical,  would  call  for  a  higher  concentration  of  salt 
than  can  be  removed  by  dissolving. 

Where  the  salt  is  to  be  removed  in  solution,  as  may  be 
done  in  exceptional  cases,  the  land  may  be  diked  in  such 
a  way  that  water  can  be  made  to  stand  several  inches  deep 
over  the  surface  for  a  number  of  hours  till  most  of  the  salt 
is  dissolved.  The  solution  is  then  drawn  off  carrying  with 
it  a  large  percentage  of  the  alkali.  Water  may  in  this 
way  be  added  and  drawn  off  several  times  in  order  to  make 
the  treatment  effective.  It  is  not  necessary  to  let  the 
water  stand  more  than  a  short  time  since  the  salt  dis- 
solves quickly  and  if  allowed  to  stand  would  reenter  the 
soil  with  percolating  water.  This  method  is  not  to  be 
recommended  under  many  conditions. 

A  method  of  reclamation  somewhat  similar  to  the  above 
requires  water  to  stand  on  the  land  for  long  periods.  By 
this  means  the  salt  is  gradually  washed  down  into  the  soil 
out  of  the  reach  of  plants.  Where  conditions  are  favor- 
able, however,  it  is  much  better  to  carry  the  salt  entirely 
out  of  the  land  by  drainage,  since  it  will  rise  again  if  simply 
washed  down. 


160       RECLAIMING  ALKALI  LANDS 

The  reclamation  of  land  by  flooding  is  used  extensively 
in  the  lower  Nile  Valley  in  Egypt.  Details  of  the  methods 
used  are  described  by  Means  (12).  After  land  has  been 
reclaimed  by  flooding  it  is  desirable  to  raise  a  crop  that 
can  endure  alkali  and  water  till  the  soil  is  in  a  proper 
condition  for  other  crops.  Rolet  (12)  recommends  rice 
for  climates  in  which  it  will  grow.  White  sweet  clover 
(Melilotus  alba)  is  also  an  excellent  crop  for  this  purpose. 

Neutralizing  Sodium  Carbonate.  —  The  methods  used  in 
removing  most  of  the  salts  are  not  entirely  satisfactory 
for  sodium  carbonate,  or  black  alkali.  This  salt  dissolves 
organic  matter  from  the  soil  and  deflocculates  the  particles, 
thereby  injuring  the  soil  structure  and  making  the  pene- 
tration of  water  very  slow.  The  high  direct  toxicity  of 
this  salt  also  renders  it  much  more  harmful  than  the 
sulphates.  Hilgard  and  his  associates  (8),  working  in 
California,  found  that  under  suitable  conditions  sodium 
carbonate  can  be  made  to  react  with  gypsum  to  form 
sodium  sulphate  and  calcium  carbonate.  The  reaction  is 
as  follows: 

Na2C03  +  CaS04  =  Na2S04  +  CaCO3. 

This  changes  the  alkali  from  a  very  injurious  to  a  much 
less  harmful  salt. 

Shinn  and  Hilgard  (15)  used  3000  pounds  of  gypsum 
to  the  acre  in  Tulare,  California,  with  good  results.  The 
best  results  were  secured  on  plats  treated  with  gypsum  in 
connection  with  drainage.  Later  reports  of  the  experi- 
ments made  by  Hilgard  and  Loughridge  (8)  and  by 
Shinn  (14)  show  that  the  treatment  continued  to  be  suc- 
cessful. In  some  cases  gypsum  was  used  at  the  rate  of 
7.7  tons  to  the  acre  annually  for  thirteen  years  with  a 
gradual  amelioration  of  the  alkali  spots.  In  the  four 


OTHER    CHEMICAL    TREATMENTS  161 

years  following  1897  a  six-acre  vineyard  received  34,000 
pounds  of  gypsum  or  about  4^  tons  a  year.  This  was 
applied  at  a  cost  of  less  than  four  dollars  an  acre  each 
year  which  was  a  small  cost  in  proportion  to  the  returns. 

As  a  result  of  experiments  in  the  San  Luis  Valley,  Colo- 
rado, Headden  (7)  suggests  the  use  of  nine  pounds  of 
gypsum  for  each  pound  of  black  alkali  in  the  soil  and  the 
removal  of  the  alkali  by  surface  irrigation. 

Extensive  experiments  by  Breazeale  (i)  are  reported  as 
showing  that  the  field  application  of  gypsum  probably 
has  no  effect  in  overcoming  black  alkali  if  the  soil  already 
contains  soluble  sulphates  in  appreciable  quantities  or  if 
the  irrigation  water  contains  these  salts.  It  seems,  there- 
fore that  while  gypsum  is  useful  under  some  conditions, 
it  is  not  by  any  means  a  universal  panacea  for  all  black- 
alkali  troubles. 

Other  Chemical  Treatments.  —  The  use  of  chemical 
substances  other  than  gypsum  has  frequently  been  tried 
in  overcoming  alkali.  Symmonds  (17)  found  in  pot  ex- 
periments that  alkali  soil  that  was  treated  with  0.2,  0.5, 
and  i  per  cent  of  nitric  acid  produced  more  than  5 
times  the  yield  of  wheat  that  was  produced  by  the  un- 
treated soil.  He  (16)  later  carried  on  a  similar  experiment 
in  the  field  where  600  pounds  of  nitric  acid  to  the  acre  of 
land  were  mixed  with  artesian  well  water  and  sprinkled 
on  the  soil.  The  results  showed  a  great  increase  in  yield 
due  to  the  treatment. 

Lipman  (10)  has  obtained  excellent  results  in  treating 
alkali  soil  with  small  quantities  of  sulphuric  acid. 

The  use  of  stable  manure  on  alkali  land  has  long  been 
known  to  improve  it  for  crop  production.  It  has  indirect 
value  in  reducing  evaporation  as  well  as  the  more  direct 
action  on  the  soil  and  plants. 


162       RECLAIMING  ALKALI  LANDS 

Cropping  with  Alkali-resistant  Crops.  —  Allowing  land 
to  remain  uncropped  promotes  accumulation  of  alkali  at 
the  surface.  It  is  desirable,  therefore,  to  maintain  some 
kind  of  plant  growth  on  land  that  is  being  reclaimed  even 
though  the  plant  is  not  the  most  desirable.  Any  plant 
growth  is  better  than  none.  In  soils  that  are  so  highly 
alkaline  that  no  ordinary  crops  will  grow,  certain  salt 
weeds  will  thrive.  It  is  much  better  to  have  them  grow- 
ing than  for  the  land  to  be  bare.  When  these  weeds 
cover  the  land  the  temptation  is  to  burn  them,  but  such 
a  practice  leaves  the  alkali  absorbed  by  the  plant  on  the 
top  of  the  land  with  the  ash.  Some  alkali-resistant  plants 
take  up  large  quantities  of  salts,  which  might  be  perma- 
nently removed  from  the  land  if  the  weeds  were  harvested 
and  hauled  off  rather  than  being  burned  where  they  grew. 

In  Chapters  VI  and  XIV  there  is  a  full  discussion  of 
the  crops  that  do  well  on  alkali  land.  From  these  lists, 
crops  may  be  selected  for  use  during  the  various  stages 
of  reclamation. 

Drainage.  —  The  only  permanent  way  to  reclaim  alkali 
land  is  to  remove  the  excessive  salt.  This  can  best  be 
accomplished  by  some  system  of  drainage,  the  various 
types  of  which  are  described  in  Chapter  XIII.  It  may  be 
said,  therefore,  that  alkali  reclamation  and  drainage  are 
almost  synonymous  terms.  Of  course  drainage  is  not 
equally  effective  under  all  conditions.  Heavy,  compact 
soils  containing  large  quantities  of  black  alkali  respond 
slowly  to  drainage,  whereas  open  soils  which  may  contain 
large  quantities  of  sulphates  and  chlorides  may  have 
these  salts  effectively  washed  out  in  a  short  time. 

A  good  example  of  the  rate  of  removal  of  salts  is  had  in 
the  Swan  Tract  (3)  near  Salt  Lake  City.  Work  was  begun 
in  1902  on  this  forty-acre  farm  by  the  U.  S.  Department 


DRAINAGE 


163 


of  Agriculture  Bureau  of  Soils  and  the  Utah  Agricultural 
Experiment  Station  cooperating.  By  the  end  of  1903, 
5,651,776  cubic  feet,  or  51.8  per  cent,  of  the  water  added  to 
the  tract  came  out  through  the  drains.  This  water  carried 

TABLE  XVII.    ALKALI  SALTS  REMOVED  BY  DRAINAGE  DURING 
THREE  YEARS.     SWAN  TRACT  NEAR  SALT*'  LAKE  CITY 


i 

WATEI 

i  ADDED  PER 

ACRE 

SALTS 
ADDED  IN 

SALT  IN 

NET  SALTS 

MONTH 

Rain 
and 
Snow 

Irrigation 
(Acre  inches) 

Total 

(Acre  inches) 

IRRIGATION 
WATER 
(Pounds  per 
acre) 

DRAINAGE 
WATER 
(Pounds  per 
acre) 

LOST  FROM 
SOIL 
(Pounds 
per  acre) 

(Acre  inches) 

1902 

September 

1  .96 

1.96 

696.1 

3,805 

October  .  . 

6.47 

6.47 

2,288.0 

4,878 

'2,583 

November 

"I'.iS 

1.18 

8,845 

8,845 

December 

1-15 

i-i5 

4,695 

4,695 

1903 

January.  . 

2.OI 

2.OI 

9,780 

9,780 

February. 

•94 

•94 

5,370 

5,370 

March 

OI 

.91 

14,768 

14,768 

April  

.  y  J. 

77 

V 

•  77 

663 

663 

May  

•  /  / 
3-97 

5-23 

9.18 

1,858 

14,178 

.12,320 

June  

•73 

4.66 

5-38 

1,655 

8,630 

6,975 

July.../. 

•25 

11.65 

11.98 

4,138 

13,912 

9,774 

August  .  .  . 

14.62 

14.58 

5,192 

30,544 

25,352 

September 

16.20 

16.  17 

5,754 

41,353 

35,599 

October 

2.42 

2.42 

859 

21,025 

20,166 

November 

3.88 

3-87 

i,378 

3,159 

1,781 

December 

.28 

.28 

99 

1,099 

1,000 

1904 

January.  . 

1.50 

1.49 

533 

473 

60 

February. 

2.06 

2.06 

732 

11,891 

n,i59 

March 

i  .  29 

,i  .29 

458 

13,049 

12,591 

April  

1.76 

1.76 

625 

9,558 

8,933 

May  

2.64 

2.63 

938 

i,537 

599 

June  

•3i 

4.26 

4-55 

i,5i3 

787 

-726 

July  

.60 

ii  .09 

11.66 

3,939 

9,634 

5,695 

August.  .  . 

•25 

13-23 

13-35 

4,692 

17,776 

13,084 

September 

•14 

5-52 

5-65 

1,960 

14,480 

12,520 

Total  .  . 

13.21 

110.72 

123.69 

45,572 

265,889 

223,586 

164 


RECLAIMING  ALKALI  LANDS 


out  3648  tons  of  salt  over  the  measuring  weir  in  addition 
to  the  salt  washed  to  lower  depths  by  percolating. water. 
Tables  XVII  and  XVIII  show  in  detail  the  rate  of  re- 
moval of  the  salts. 

TABLE  XVIII.    QUANTITIES  OF  ALKALI  AT  DIFFERENT  DEPTHS 

OF  SOIL  ON  CERTAIN  DATES  AND  COMPOSITION  OF  DRAINAGE 

WATER.    SWAN  TRACT  NEAR  SALT  LAKE  CITY 


SOIL 
SECTION 

SEPTEMBER,  1902 

MAY,  1903 

OCTOBER,  1903 

OCTOBER,  1904 

Alkali 
in 
Soil 
(p.p.m.) 

Part  of 
4  ft. 
Total 
(per  cent) 

Alkali 
in 
Soil 
(p.p.m. 

Part  of 
4  ft. 
Total 
(per  cent) 

Alkali 
in 
Soil 
(p.p.m.) 

Part  of 
4  ft. 
Total 
(per  cent) 

Alkali 
in 
Soil 
(p.p.m.) 

Part  <5f 
4  ft. 
Total 
(percent) 

First  Foot.  .  .  . 
Second  Foot.  . 
Third  Foot.  .  . 
Fourth  Foot.  . 

17,038 
19,250 
22,075 
24,775 

20 

23 

27 
30 

6,238 
8,125 
13,325 
I5,8l3 

14 
19 
31 
63 

1,263 
2,288 

4,125 
7,608 

8 

IS 

28 

49 

475 
i,  600 
2,650 
6,250 

4 
13 

24 
57 

Total  

83,138 

43,501 

15,284 

10,975 

-• 

Average  

20,785 

10,875 

3,821 

2,744 

Chemical  Analysis  of  Drainage  Water  (in  Parts  per  1,000,000) 


Seepage  Water 

Constituent 

from  Tile 
Drain  before 

Drainage 
Water, 

Drainage 
Water, 

Drainage 
Water, 

Drainage 

Water, 

Irrigating, 

June  18,  1903 

April  4,  1904 

May  10,  1905 

June  26,  1906 

Oct.  9,  1902 

Ca.. 

4.C 

72 

6l 

27 

•27 

Mg.  . 

96 

2C7 

162 

7O 

80 

Na  

6,966 

11,771 

7,262 

3,660 

3,924 

K  

319 

260 

269 

108 

126 

SO4  

•2    8?O 

8  886 

2    CJ^I 

2  14? 

2,288 

Cl  

7,650 

12,070 

8,881 

3,958 

4,312 

HC03  

1,329 

937 

800 

666 

695 

C03  

71 

55 

40 

59 

60 

Total  Solids  . 

20,346 

34,3o8 

21,006 

10,701 

n,53l 

DRAINAGE  165 

Hart  (6)  gives  an  example  of  a  tract  on  which  before 
drainage  the  ground  water  stood  within  2  feet  of  the 
surface.  A  white  crust  of  salts  covered  the  surface  and 
nothing  of  value  grew  on  the  land,  the  only  vegetation 
being  an  occasional  salt  weed.  The  average  salt  content 
for  the  first  4  feet  of  depth  was  2.25  per  cent.  A  drain- 
age system  was  installed  and  in  a  month  so  much  of  the 
excess  water  in  the  soil  was  removed,  that  the  water- 
table  was  practically  down  to  the  level  of  the  drains. 
The  drainage  water  was  very  high  in  salt.  By  the  end  of 
the  month  an  analysis  showed  the  salt  content  of  the  soil 
to  have  been  reduced  to  i  per  cent.  The  ground  surface 
was  cultivated  and  irrigated  with  a  limited  supply  of  water 
and  crops  were  planted.  These  gave  only  fair  results. 
Meanwhile  the  higher  temperature  of  summer  had  in- 
creased evaporation  and  the  average  salt  content  for  4 
feet  was  found  to  have  increased  to  1.28  per  cent  in  spite 
of  drainage.  A  near-by  uncultivated  and  unirrigated  spot 
which  had  been  affected  to  some  extent  by  the  drainage 
system  showed  an  average  salt  content  for  the  first  four 
feet  of  1.51  per  cent.  It  was  evident  that  drainage  alone 
would  never  reclaim  the  tract;  hence,  a  heavy  flooding 
was  given  which  reduced  the  average  salt  content  for  the 
first  4  feet  to  0.43  per  cent,  less  than  one-fifth  of  the  origi- 
nal content.  At  the  same  time  the  near-by  uncultivated 
spot  showed  an  average  salt  content  for  the  first  4  feet  of 
1.73  per  cent,  an  increase  which  was  caused  by  percolation 
from  flooding  the  adjacent  land. 

Thousands  of  examples  could  be  given  to  show  the 
effectiveness  of  drainage  in  reclaiming  alkali  lands.  Many 
failures  have  also  been  recorded.  These  have  resulted 
from  improper  methods  which  were  decided  on  before  all 
conditions  were  studied  and  also  from  the  fact  that  the 
drainage  system  was  expected  to  do  everything. 


166  RECLAIMING  ALKALI  LANDS 


REFERENCES 

1.  BREAZEALE,  J.  F.    Formation  of  "Black  Alkali"  (Sodium  Carbonate) 

in  Calcareous  Soils.     Jour.  Agr.  Rsch.  10  (1917),  pp.  541-590. 

2.  BROWN,  C.  F.,  and  HART,  R.  A.     The  Reclamation  of  Seeped  and 

Alkali  Lands,  Utah  Sta.  Bui.  in   (1910),  pp.  75-92. 

3.  DORSEY,  C.  W.     Alkali  Soils  of  the  United  States.     U.  S.  D.  A.  Bur. 

of  Soils,  Bui.  35  (1906),  179  pp. 

4.  HARRIS,  F.  S.    The  Movement  of  Soluble  Salts  with  Soil  Moisture, 

Utah  Sta.  Bui.  139  (1915),  pp.  119-124. 

5.  HARRIS,  F.  S.,  and  ROBINSON,  J.  S.     Factors  Affecting  the  Evapora- 

tion of  Moisture  from  the  Soil.     Jour.  Agr.  Rsch.  7  (1916),  pp.  439- 
461. 

6.  HART,  R.  A.    The  Drainage  of  Irrigated  Farms.     U.  S.  D.  A.  Farmers' 

Bui.  805  (1917),  31  PP- 

7.  HEADDEN,  W.  P.     "Black  Alkali"  in  the  San  Luis  Valley.     Colo.  Sta. 

Bui.  231  (1917),  PP-  3-i5. 

8.  HILGARD,  E.  W.,  and  LOUGHRIDGE,  R.  H.    The  Distribution  of  the 

Salts  in  Alkali  Soils.     Cal.  Sta.  Rpt.  1895,  pp.  37-69. 

9.  HILGARD,  E.  W.     Soils,  pp.  455-484.     (New  York,  1906.) 

10.  LIPMAN,  C.  B.     New  Experiments  on  Alkali  Soil  Treatment,  Univ. 

Cal.  Pub.  Agr.  Sci.  i  (1915),  pp.  275-290. 

11.  MEANS,  T.  H.     Reclamation  of  Alkali  Lands  in  Egypt.     U.  S.  D.  A. 

Bur.  of  Soils,  Bui.  21  (1903),  48  pp. 

12.  ROLET,  A.     Cultivation  of   Salt  Lands.     Jour.   Agr.  Prat.  n.  scr.  9 

(1905),  No.  22,  pp.  710-712.     (Abs.  E.  S.  R.  17,  p.  814.) 

13.  SANDSTEN,  E.  P.     Reclaiming  Niter  Soil  in  the  Grand  Valley.     Colo. 

Sta.  Bui.  235  (1917),  8  pp. 

14.  SHINN,  C.  H.     Alkali  Reclamation  at  Tulare  Substation.     Cal.  Sta. 

Rpt.  1899-1901,  Pt.  II,  pp.  204-213. 

15.  SHINN,  C.  H.,  and  HILGARD,  E.  W.     Reclamation  of  Alkali  Land  with 

Gypsum  at  the  Tulare  Station.     Cal.  Sta.  Rpt.  1893-94,  pp.  145- 
149. 

16.  SYMMONDS,  R.  S.     Experiments  with  Nitric  Acid  in  Alkaline  Soils. 

Agr.  Gaz.  N.  S.  Wales,  21  (1910),  No.  3,  pp.  257-266. 

17.  SYMMONDS,  R.   S.     Note  on  Action  of  Nitric  Acid  in  Neutralizing 

Alkaline  Soil.     Jour,  and  Proc.  Roy.  Soc.  N.  S.  Wales,  41  (1907), 
pp.  46-48. 

18.  TINSLEY,  J.  D.     Drainage  and  Flooding  for  the  Removal  of  Alkali. 

N.  Mex.  Sta.  Bui.  43  (1902),  29  pp. 

19.  WEIR,  W.  W.     A  Preliminary  Report  of  the  Kearney  Vineyard  Ex- 

perimental Drain.     Cal.  Sta.  Bui.  273  (1916),  pp.  103-123. 


CHAPTER  XIII 
PRACTICAL   DRAINAGE 

DURING  the  early  years  of  irrigation  in  America  no 
provision  was  made  to  remove  the  excess  water  that  always 
collects  in  the  lowlands  of  irrigated  districts.  This  is  one 
of  the  chief  reasons  for  the  accumulation  of  alkali.  The 
modern  up-to-date  irrigation  system  should  include  some 
method  of  drainage  whereby  any  excess  of  water  is  carried 
out  of  the  land;  for  there  are  always  a  few  farmers  who, 
to  the  detriment  of  themselves  and  their  neighbors,  use 
too  much  water.  A  drainage  system  laid  out  at  the  same 
time  as  the  irrigation  system  will  in  some  cases  be  more 
simple  than  one  installed  after  the  land  becomes  a  bog. 
In  swampy  places  drain  ditches  are  constructed  with 
difficulty  and  tile  cannot  be  laid  evenly  and  securely. 
Unfortunately,  the  reclamation  of  most  alkali  land  is  not 
undertaken  until  after  the  condition  has  become  bad. 
This  means  that  many  difficulties  are  encountered.  Of 
course  it  would  not  be  wise  to  install  drainage  when  the 
irrigation  system  is  put  in  unless  there  is  likelihood  of 
water-logging.  The  problem  is  doubly  complex  since  not 
only  must  the  excess  soil  water  be  removed  but  the  alkali 
must  also  be  washed  out. 

Advantages  of  Drainage.  —  Where  drainage  systems  are 
installed  on  land  there  is  generally  a  complete  transforma- 
tion; many  conditions  favoring  crop  growth  are  improved. 
Most  important  in  an  alkali  soil  is  the  removal  of  the 
excessive  salt.  In  many  soils  where  the  salt  content  is 

167 


168 


PRACTICAL  DRAINAGE 


not  high  enough  entirely  to  prevent  crop  growth,  there  is 
sufficient  to  reduce  the  yield  to  a  point  that  is  unprofit- 
able. The  expenses  are  practically  the  same  in  raising 
half  a  crop  as  a  full  one.  In  the  one  case  farming  is  carried 
on  at  a  loss,  and  in  the  other  a  good  profit  may  be  realized. 
Thus,  removing  alkali  by  drainage  may  make  highly  pro- 
ductive millions  of  acres  of  land  that  is  only  moderately 


FIG.  20.  —  FIELD  READY  FOR  LAYING  TILE. 

successful.  There  are  also  millions  of  acres  at  present 
wholly  unproductive  that  may  be  made  to  yield  bounte- 
ously by  removing  the  alkali. 

Drainage  removes  the  excessive  water  from  the  soil. 
By  lowering  the  water-table  the  plant  is  given  a  larger  root 
zone  from  which  to  draw  both  food  and  water.  If  only 
the  surface  foot  or  two  can  be  drawn  on  for  food  the  plant 
cannot  be  expected  to  be  so  well  supplied  with  nourish- 
ment as  it  would  with  a  feeding  area  of  five  or  six  feet. 


ADVANTAGES  OF   DRAINAGE  169 

Strange  as  it  may  seem,  drainage  increases  the  water 
supply  of  the  plant  and  reduces  the  injury  that  is  likely 
to  be  caused  by  drought.  Roots  do  not  readily  penetrate 
into  the  ground  water.  They  are  confined  to  the  zone 
above  the  water-table  from  which  they  absorb  capillary 
water.  Free  water  is  unavailable  to  them;  A  water-table 
near  the  surface  means,  therefore,  that  the  plant  can  absorb 
water  from  only  a  limited  area.  In  case  of  drought  when 
the  water-table  is  likely  to  be  lowered  rapidly  the  plant 
has  but  a  shallow  root  system  which  is  unable  to  endure 
drought  so  well  as  a  root  system  which  extends  well  into  the 
soil  and  is  able  to  take  up  moisture  from  a  deep  soil  zone. 

Drainage  allows  the  soil  to  become  warm  early  in  spring. 
The  high  specific  heat  of  water  makes  it  slow  to  become 
warm.  This  has  great  practical  significance  since  a  slow, 
cold  soil  delays  spring  work  and  retards  the  development 
of  the  young  plant  at  a  critical  period  in  its  life  history. 

Roots  require  air  for  their  normal  functioning.  If  free 
circulation  of  air  through  the  soil  is  retarded  by  water- 
logging, the  plant  does  not  get  sufficient  air  for  its  best 
growth.  This  condition  reflects  itself  in  the  yield.  Covered 
drains  promote  the  free  movement  of  air  through  the  soil; 
this  may  help  to  account  for  the  wonderful  results  that 
follow  drainage  in  cases  where  the  water-table  is  not  close 
to  the  surface  and  alkali  is  not  injurious. 

Going  hand  in  hand  with  better  aeration  is  the  better 
condition  for  the  growth  of  desirable  microorganisms. 
Decay  of  vegetation  in  absence  of  sufficient  air  takes  place 
as  putrefaction  which  results  in  products  toxic  to  plant 
growth.  Nitrification,  nitrogen-fixation,  and  normal  plant 
decay  require  air.  If  it  is  not  present  the  organisms 
promoting  these  beneficial  processes  will  be  replaced  by 
undesirable  ones. 


170  PRACTICAL  DRAINAGE 

Water-logged  land  has  a  tendency  to  heave  in  freezing. 
This  results  in  the  winter-killing  of  such  crops  as  alfalfa, 
clover,  and  fall  grains.  Where  the  soil  is  not  covered  with 
a  protective  layer  of  snow,  winter-killing  may  be  one  of 
the  most  serious  handicaps  to  farming.  Anything  that 
reduces  it  will  add  greatly  to  the  farmer's  profits. 

The  tilth,  or  structure,  of  the  soil  is  benefited  by  drain- 
age. An  undrained  soil  puddles  readily,  whereas  one  that 
is  drained  tends  to  form  the  crumb-like  structure  which 
is  sought  by  the  farmer. 

Determining  the  Need  of  Drainage.  —  As  with  all  other 
expenses,  that  required  for  drainage  should  be  investigated 
before  it  is  incurred.  It  would  of  course  be  folly  to  spend 
15  or  20  dollars  an  acre  draining  land  that  would  not  be 
benefited  thereby.  Drainage  is  usually  carried  on  to  re- 
move either  excess  water  or  excess  alkali.  In  spite  of 
secondary  benefits,  it  is  doubtful  if  it  would  pay  to  drain 
in  most  cases  unless  one  of  these  undesirable  conditions 
existed. 

An  excess  of  water  can  easily  be  determined  by  boring 
test  holes  with  a  soil  auger.  The  surface  indications  are 
not  an  absolutely  reliable  guide.  In  many  soils  having  a 
dry,  baked  crust  at  the  surface,  borings  will  reveal  free 
water  2  or  3  feet  below  the  surface.  The  color  and  thrift 
of  the  vegetation  are  valuable  aids  in  determining  the  need 
of  drainage,  but  the  final  test  should  be  made  by  the 
use  of  an  auger. 

Excessive  quantities  of  alkali  can  readily  be  determined 
by  a  chemical  analysis.  Water  extracts  of  the  soil  can 
easily  be  tested  for  chlorides,  sulphates,  carbonates,  and 
nitrates.  With  information  of  this  sort  available  it  is 
possible  to  say  whether  or  not  some  of  the  salts  should  be 
removed.  The  electrolytic  bridge  is  very  useful  in  this 


TYPES    OF    DRAINS 


171 


connection  to  determine  the  approximate  concentration 
of  total  soluble  salts.  For  exact  work,  chemical  methods 
should  be  resorted  to,  but  for  general  reconnoissance 
work  the  bridge  can  be  used  to  advantage. 

Types  of  Drains.  —  After  deciding  that  the  land  needs 
drainage,  the  next  point  to  settle  is  the  type  of  system  to 


FIG.  21.  —  BOGGY  ALKALI  LAND  THAT  is 
WITH  SHORT  TILE. 


TO  DRAIN 


install.  No  one  system  is  best  for  all  conditions.  On 
some  projects  a  combination  of  systems  can  be  used  to 
advantage. 

The  open  drain  on  account  of  its  low  initial  cost  has 
been  used  rather  extensively.  It  has  some  advantages 
and  many  disadvantages.  Among  its  advantages  is  the 
fact  that  its  action  is  at  all  times  under  the  observation 
of  the  farmer.  Any  obstruction  can  easily  be  found  and 
removed.  The  fact  that  the  farmer  can  do  most  of  the 


172 


PRACTICAL  DRAINAGE 


work  himself  at  odd  times  and  does  not  have  to  pay  for 
materials  makes  it  possible  at  times  to  put  in  an  open 
ditch,  whereas  a  closed  drain  would  be  beyond  his  reach. 
Among  the  disadvantages  of  the  open  drain  are  the  facts 
that  the  original  cost  does  not  represent  the  total  outlay. 
Every  year,  and  often  several  times  during  the  year, 
open  drains  must  be  cleaned.  The  banks  cave  off  or 
other  obstructions  fall  in  and  interfere  with  the  effective- 


FIG.  22.  —  OPEN  DITCH  USED  TO  CARRY  AWAY  THE  DRAINAGE  WATER 
FROM  A  LARGE  AREA.    COVERED  DRAINS  EMPTY  INTO  THIS  DITCH. 

ness  of  the  drain.  Weeds  growing  on  the  banks  and  in 
the  bottom  of  the  ditch  are  a  constant  source  of  annoy- 
ance. Considerable  land  that  could  be  cultivated  if  the 
drain  were  covered  is  made  useless  by  the  open  ditch, 
which  also  cuts  the  land  up  into  smaller  fields  causing 
inconvenience  in  plowing  and  performing  the  other  farm- 
ing operations.  Open  ditches  are  always  a  source  of  danger 
for  farm  animals  that  may  fall  in  them  and  be  injured. 
These  many  disadvantages  usually  turn  the  preference 
toward  some  form  of  covered  drain,  except  in  such  cases 


TYPES   OF   DRAINS 


173 


as  require  a  main  drain  to  carry  off  large  quantities  of 
water.  Several  closed  drains  may  open  into  a  main  open 
ditch. 

Many  types  of  closed  drains  are  in  operation.  The 
main  requirement  is  to  preserve  through  the  subsoil  an 
open  channel  that  will  carry  off  percolating  waters.  A 


FIG.  23.  —  MACHINE  FOR  MAKING  DRAINS  IN  HEAVY  SOIL  WITHOUT 
THE  USE  OF  TILE. 

ditch  is  dug  and  some  material  that  will  maintain  the 
channel  open  placed  in  it.  Rocks,  brush,  straw,  timber, 
and  tile  are  all  used. 

In  certain  heavy  gumbo  soils  a  special  device  known  as 
a  gopher  machine,  shown  in  Fig.  23,  makes  a  hole  through 
the  soil  that  does  not  require  filling.  In  this  device  a  tor- 
pedo about  8  inches  in  diameter  is  attached  to  a  subsoiling 
point,  which  is  held  in  the  ground  by  a  heavy  wheeled 
frame.  The  depth  at  which  the  torpedo  is  pulled  through 


174  PRACTICAL  DRAINAGE 

the  soil  can  be  regulated  by  the  operator.  In  making 
drains  this  machine  begins  at  the  outlet  end  and  moves 
toward  the  higher  land  leaving  a  gopher-like  hole  through 
which  the  drainage  water  passes.  Such  drains  can  be  made 
25  feet  apart  for  about  $5  an  acre.  These  will  last  5  or  6 
years  in  the  right  kind  of  soil.  If  any  of  them  happen  to 
become  clogged,  new  ones  may  be  made  between  the  others. 

The  type  of  covered  drain  to  use  depends  on  a  number 
of  factors.  In  wet  brush  land  where  rock  and  lumber  are 
scarce  and  where  tile  cannot  be  had,  rush  and  straw  may 
be  used  to  good  advantage,  although  usually  less  ef- 
ficiently than  some  of  the  more  permanent  types. 

Brown  and  Hart  (3)  found  lumber  drains  to  be  very 
effective  in  a  swamped  soil  that  would  not  remain  firm 
enough  to  hold  tile.  Rock  properly  placed  in  the  trench 
has  long  been  used  to  keep  open  the  water  channel. 

These  various  unusual  types  of  drains  are  unimportant 
in  comparison  with  tile.  The  most  common  kinds  are 
clay  tile,  either  porous  or  vitrified.  Many  types  of  clay 
tile  are  to  be  had.  These  are  so  well  and  favorably  known 
that  further  discussion  seems  unnecessary  here.  Cement 
tile  is  being  used  to  some  extent,  but  its  use  on  alkali  land 
is  attended  with  some  risk  which  is  explained  below. 

Cement  Tile  for  Alkali  Land.  —  The  ease  with  which 
cement  tile  can  be  made  in  some  localities  has  encouraged 
its  use  for  drainage.  This  has  often  resulted  in  failure, 
because  it  has  been  found  that  under  certain  conditions 
the  cement  is  attacked  and  destroyed  by  some  of  the  al- 
kali salts.  This  observation  has  led  to  considerable  study 
on 'the  relation  of  soluble  salts  to  cements  and  their  de- 
terioration. 

Burke  and  Pinckney  (4)  found  that  to  cause  weakening 
it  was  necessary  for  salt  solutions  to  penetrate  the  concrete. 


CEMENT  TILE  FOR  ALKALI  LAND 


175 


Weakening  results  from  the  formation  of  compounds  that 
expand  and  break  up  the  concrete.  Later  the  soluble 
compounds  leach  out  leaving  the  material  not  nearly  so 


FIG.  24.  —  POORLY  MADE  CEMENT  THAT  is  BEING 
CRUMBLED  BY  ALKALI. 

strong.  Neat  cement  that  excluded  absorption  was  not 
injured  by  alkali  solutions.  Meade  (9)  found  that  even 
very  dilute  solutions  of  the  salts  of  magnesium  and  the 
sulphates  in  general  have  a  destructive  action  on  concrete. 
Cements  low  in  alumina  were  less  affected  than  others. 


176  PRACTICAL  DRAINAGE 

Work  done  at  the  U.  S.  Bureau  of  Standards  (i,  14) 
shows  how  Portland  cement  concrete  mortar,  if  porous, 
can  be  disintegrated  by  the  mechanical  force  exerted  by 
the  crystallization  of  salts  in  its  pore  spaces.  Mixtures 
leaner  than  one  part  cement  to  three  parts  of  aggregate 
were  found  to  be  unsuitable  for  use  in  localities  having  a 
soil  high  in  alkali. 

Headden  (6)  found  that  in  the  presence  of  solutions  of 
sodium  sulphate  and  sodium  carbonate  a  chemical  de- 
composition of  the  cement  takes  place  with  a  removal 
of  silicic  acid  and  lime  which  destroys  the  cohesiveness  of 
the  concrete. 

Steik  (12)  found  that,  of  the  great  number  of  solutions 
tested,  the  5  per  cent  sodium  sulphate  had  the  greatest 
disintegrating  action.  Solutions  containing  chlorides,  sul- 
phates, and  carbonates  all  had  some  effect.  Mortars  were 
found  to  disintegrate  faster  than  neat  cement,  which  is 
similar  to  the  findings  of  Sims  and  Dieckman  (n).  The 
latter  author  found  that  density  and  age  are  very  important 
factors  in  helping  cement  to  resist  alkali.  Steik  believes 
that  the  ultimate  cause  of  the  disintegration  of  cement 
by  alkalies  is  due  to  the  formation  of  compounds  in  the 
cement,  which  subsequently  are  removed  by  solution. 

These  experiments  all  show  the  necessity  for  care  in 
the  use  of  cement  tile  to  drain  alkali  land,  but  if  the  cement 
is  properly  made  it  is  fairly  satisfactory. 

Preliminary  Survey.  —  Before  actual  trenching  is  be- 
gun it  is  important  to  make  a  preliminary  survey  to  de- 
termine the  nature  of  the  subsoil  and  the  slope  of  the  land 
to  be  drained.  A  great  many  test  holes  made  with  an 
auger  will  reveal  the  location  of  pervious  and  impervious 
strata.  This  information  is  necessary  in  deciding  the 
depth,  location,  and  direction  of  the  drains.  A  system 


LAYING   OUT   THE   SYSTEM 


177 


installed  without   taking  account  of   these   conditions  is 
likely  to  be  inefficient  and  expensive. 

Laying  out  the  System.  —  After  the  preliminary  survey 
is  made  the  system  can  be  laid  out  and  the  location  and 
depth  of  each  drain  determined.  The  district  should  be 


FIG.  25.  —  METHOD  or  ESTABLISHING  GRADE  OF 
DRAINS 


mapped  in  such  a  way  that  the  data  obtained  in  the  pre- 
liminary survey  will  show  the  contour  of  the  surface,  the 
texture  of  the  soil  and  subsoil,  and  the  ground-water 
condition.  On  this  map  the  drainage  system  may  be 
drawn  in  such  a  way  that  intersecting  joints,  the  sizes  of 
tile,  and  other  data  can  be  preserved  for  future  use.  These 
data  are  extremely  valuable  in  locating  trouble.  The 
memory  is  not  sufficiently  accurate  to  be  relied  on  for  this 


178  PRACTICAL  DRAINAGE 

information,  and  it  is  a  good  idea  to  preserve  the  record 
for  the  use  of  some  one  besides  the  original  drainer  of  the 
land. 

In  laying  out  the  system  the  depth  of  the  drains,  the 
size  of  tile,  the  slope  of  the  drain,  and  the  distance  apart 
must  be  given  careful  consideration  and  will  vary  with 
each  set  of  conditions.  These  factors  depend  somewhat 
upon  each  other.  For  example,  the  steeper  the  grade 
the  smaller  the  tile  may  be,  and  the  deeper  the  drain  the 
farther  apart  they  may  be  placed.  In  general,  tile  should 
be  placed  from  5  to  7  feet  deep  and  the  space  between 
tile  lines  will  usually  vary  from  200  to  1000  feet. 

Size  of  Drains.  • —  A  number  of  formulas  have  been 
worked  out  to  help  in  deciding  the  size  of  tiles  that  will  be 
efficient  and  economical.  Poncelet's  formula  for  de- 
termining the  velocity  of  flow  in  drains,  which  has  found 
considerable  use,  is  as  follows: 


+  S4D 
in  which 

V  =  Velocity  in  feet  per  second, 
D  =  Diameter  of  tile  in  feet, 
F  =  Total  fall  of  drain  in  feet, 
L  =  Length  of  drain  in  feet. 

Knowing  the  velocity  of  flow  in  a  tile  of  given  diameter 
the  discharge  may  be  determined  by  using  the  general 
formula : 

Q  =  AV 
in  which 

Q  =  Discharge  in  cubic  feet  per  second,  and 
A  =  Cross-section  area  of  tile  in  square  feet. 


SIZE   OF  DRAINS  179 

The  number  of  acres  drained  is  found  by  dividing  the 
discharge  by  a  constant  representing  the  number  of  cubic 
feet  per  second  necessary  to  relieve  one  acre  of  a  given 
depth  of  water  in  24  hours.  The  constants  most  used 
are: 

0.0052  cu.  ft.  per  second  =  |  in.  per  acre  in  24  hours 
0.0105  "     "     "        "       =  I   "    "      "     "  24      " 
0.0140  "     "     "        "      - 1   "     "      "     "  24      " 

0.0210   '"       "       "  "          =  I    "      "         "       "     24         " 

0.0315  "  "  "     "    =  I  "  "    "  "  24    " 
0.0420  "   "  "     "    =  I  "  "    "   "  24    " 

In  using  the  formula,  the  number  of  acres  in  the  water- 
shed multiplied  by  the  assumed  constant  may  be  sub- 
stituted for  Q  and  the  formula  solved  for  the  diameter  of 
the  tile.  Other  methods  of  computing  sizes,  such  as  the 
Chezy-Kutter  formula  given  by  Parsons  (10),  are  used. 

Hart  (5)  has  the  following  to  say  about  the  size  of  drains 
for  irrigated  lands  and  construction  methods: 

"The  spacing  of  drains  in  the  irrigated  section  usually 
is  much  greater  than  in  humid  sections  and  frequently 
a  single  line  of  drain  may  effect  the  reclamation  of  a  con- 
siderable acreage.  From  this  it  will  be  concluded  that 
larger  drains  will  be  required  in  the  drainage  of  irrigated 
lands.  It  has  been  found  that  they  need  not  be  propor- 
tionately large,  however,  since  the  amount  of  water  which 
it  is  necessary  to  take  care  of  is  smaller  for  a  given  acreage. 
In  the  arid  section,  there  is  likely  to  be  a  continuous 
discharge  of  drainage  water  throughout  the  year,  and 
frequently  the  discharge  is  very  uniform  at  all  times. 
However,  there  are  certain  maximum  flows,  usually  during 
the  period  of  greatest  irrigation  application,  and  it  is  neces- 
sary to  provide  a  drainage  capacity  that  will  take  care  of 
such  flows. 


180 


PRACTICAL  DRAINAGE 


"If  only  the  required  capacity  of  the  drain  were  con- 
sidered, it  would  be  found  feasible  to  do  a  great  deal  of 
drainage  with  4-inch  and  5-inch  tile,  but  experience  has 
shown  that  the  use  of  tile  smaller  than  5-inch  is  not  satis- 
factory, while  5-inch  should  be  used  only  for  short  branch 
lines  or  at  the  upper  ends  of  branch  lines.  The  following 


(a)  (b) 

FIG.  26. —  TYPES  OF  LUMBER  DRAINS  USED  TO 
RECLAIM  BOGGY  ALKALI  LAND. 

table  is  offered  for  purposes  of  comparing  the  carrying 
capacity  of  tile  lines  of  different  sizes,  on  the  assumption 
that  all  are  laid  on  the  same  grade. 

TABLE  XIX.     RELATIVE  CARRYING  CAPACITIES  OF  TILE  OF 
DIFFERENT  SIZES 


One 


6-inch  tile 

7-inch  tile 

8-inch  tile 

lo-inch  tile 

i2Mnch  tile 


Will  carry  the  discharge  of 


Two  5-inch  tiles 

One  6-inch  and  one  5-inch  tile 

Two  6-inch  tiles 

One  8-inch  tile  and  one  7-inch  tile 

One  lo-inch,  one  8-inch,  and  5-inch  tile;  or  three 

8-inch   tiles;    or  seven  6-inch  tiles;    or   twelve 

5-inch  tiles 


SIZE   OF    DRAINS 


181 


"As  a  rule,  tile  larger  than  12  inches  in  diameter  is  not 
used  in  individual  farm  drainage. 

"The  size  of  tile  required  depends  on  the  amount  of 
water  to  be  carried  and  on  the  slope  of  the  drain.  The 
latter  can  be  decided  upon  when  the  survey  of  the  land 
is  made  and  the  fall  to  the  outlet  is  ^measured.  The 
former  is  not  so  easy  to  determine.  It  depends  on  the 
location  of  the  tract,  the  nature  of  the  soil,  the  slope  of 
the  ground  both  on  the  tract  and  above  it;  on  the  quantity 
of  water  used  in  irrigation  and  on  the  method  of  irrigating, 
both  on  the  tract  and  on  higher  land;  on  the  rainfall  and 
evaporation;  on  the  seepage  from  reservoirs,  canals,  and 
ditches;  and  on  many  other  factors.  Indeed,  the  de- 
termination of  the  required  capacity  of  a  drainage  system 
is  the  most  difficult  problem  confronting  drainage  engi- 
neers, and  demands  their  best  efforts.  Intricate  measure- 
ments and  calculations  must  be  made  in  each  instance.  It 
is  therefore  impossible  to  give  definite  instructions  in  re- 
gard to  this  important  matter.  It  is  possible,  however, 
to  give  a  general  idea  of  required  sizes  based  on  a  wide 
experience  under  a  great  variety  of  conditions.  The  fol- 
lowing table  is  intended  to  apply  to  fairly  uniform  land 

TABLE  XX.    SIZE  OF  TILE  REQUIRED  TO  DRAIN  GIVEN  AREAS 
HAVING  DIFFERENT  TYPES  OF  SOIL 


AREA  OF 

SIZE  OF  TILE  REQUIRED 

(in  acres) 

Clay  with  Sand  Stratum 

Sand 

32O 

lo-inch 

1  60 

8-inch 

1  2-inch 

80 

7-inch 

lo-inch 

1  2-inch 

40 

6-inch 

8-inch 

lo-inch 

20 

5-inch 

7-inch 

8-inch 

10 

5-inch 

6-inch 

8-inch 

182 


PRACTICAL  DRAINAGE 


not  located  at  the  foot  of  steeper  slopes  or  benches,  nor 
in  pockets  or  depressions,  nor  in  flat  river  bottoms  where 
it  will  receive  surface  run-off  from  higher  land,  nor  where 
it  will  receive  water  from  deep  sources  by  pressure.  The 
assumed  slope  of  the  tile  is  2  feet  per  thousand  feet. 

"If  the  soil  be  compact  clay,  a  given  size  of  tile  will 
drain  larger  areas  than  indicated.  If  the  subsoil  be  joined 
clay,  .the  'sand'  table  should  be  used.  If  the  drain  be 
located  at  the  foot  of  a  bench  or  in  a  gravel  pocket,  none 
of  the  above  bases  will  apply.  A  better  basis  for  design 
in  such  cases  is  the  length  of  a  given  size  of  tile  which  it 
is  safe  to  use.  A  slope  of  2  feet  per  1000  feet  is  assumed, 
as  before.  The  following  table  will  give  a  rough  idea: 

TABLE  XXI.     SIZES  OF  TILE  REQUIRED  FOR  DRAINS  OF  DIFFERENT 

LENGTHS 


SIZE  OF  TILE 

MAXIMUM  LENGTH 

Sand  Stratum 

Gravel 

12-inch 

Feet 
558o. 

3350 
1790 
1250 
800 
450 

Feet 

1250 
750 
400 
280 
1  80 

IOO 

lo-inch  .  .                                                .    . 

8-inch  

7  inch  
6-inch  
5-inch  .'  

uFor  greater  slopes  smaller  tile  is  required,  and  for 
flatter  slopes  larger  tile  is  necessary,  the  variation  in 
capacity  being  as  the  square  root  of  the  slope.  If  lumber 
boxes  are  used,  the  openings  should  be  about  the  square 
of  the  tile  diameter. 

"For  open  ditches  the  bottom  width  should  be  4  feet 
and  the  side  slopes  should  be  at  least  i  to  i.  Thus  for  a 
depth  of  6  feet  the  top  width  would  be  16  feet  or  more, 


CONSTRUCTION  METHODS  183 

and  for  a  depth  of  8  feet  the  top  width  would  be  20  feet 
or  more. 

"In  the  installation  of  a  drainage  system  it  should  be 
borne  in  mind  that  the  improvement  is  permanent,  and 
that  after  the  tile  is  once  covered  up  it  is  more  expensive 
to  uncover  and  relay  it  with  larger  tile  than  to  install  a 
new  drain,  so  it  is  false  economy  to  cut  down  on  the  size 
of  tile.  It  is  much  better  to  err  on  the  side  of  too  great 
capacity  than  too  small. 

4  *  Construction  Methods.  —  In  many  instances  owing  to 
lack  of  humus  the  soils  of  the  arid  region  are  very  fluxible 
when  wet  and  the  construction  of  drainage  systems  is  very 
difficult  and  requires  painstaking  care  and  ingenuity. 
Special  methods  and  devices  have  to  be  employed,  and 
special 'machinery  has  been  developed. 

"  Drain  lines  must  be  laid  out  carefully  and  grade  stakes 
set.  The  completed  drain  must  be  true  to  grade  and  as 
straight  as  possible.  For  hand  trenching  it  is  advisable 
to  stretch  a  cord  on  the  ground  along  one  edge  of  the 
proposed  trench,  to  obtain  good  alignment.  To  insure 
accurate  grade  at  all  points,  grade  plants  should  be  set 
up  at  each  station  at  a  uniform  height  above  the  grade  of 
the  drain.  A  stout  cord  then  may  be  stretched  over  the 
middle  line  of  the  trench  from  plank  to  plank  and  every 
point  on  this  cord  will  be  the  given  height  above  grade. 
Grade  may  be  established  at  one  end  of  each  tile  with  a 
grade  pole  having  a  length  equal  to  the  distance  from  the 
cord  to  the  proper  location  for  the  tile.  This  may  be 
accomplished  by  keeping  the  cord  taut  by  suspending  a 
tile  or  other  weight  at  each  end  and  measuring  down 
from  the  cord  at  the  desired  points. 

"Construction  work  always  should  start  at  the  outlet 
of  each  line  and  proceed  up  the  slope,  so  that  the  water 
developed  will  drain  away. 


184  PRACTICAL  DRAINAGE 


I 


FIG.  27.  —  WOOD  DRAINS  BEING  USED  TO  DRAIN  BOGGY  ALKALI 
LAND. 


CONSTRUCTION  METHODS  185 

"In  installing  covered  drains  either  hand  labor  or  trench- 
ing machinery  may  be  used.  Frequently,  on  small  proj- 
ects, hand  trenching  is  cheaper,  but  usually  on  larger 
projects  machines  can  do  the  work  more  rapidly,  economi- 
cally, and  satisfactorily.  It  is  preferable  to  let  a  contract 
for  the  work  to  an  experienced  and  capable  contractor. 

"If  hand  labor  is  used  it  usually  is  necessary  to  operate 
with  small  gangs,  ordinarily  about  a  half  dozen  men  to 
the  line,  as  the  trench  must  be  opened  from  the  top  to 
the  bottom  as  rapidly  as  possible  and  the  tile  laid  and 
blinded  before  caving  takes  place.  The  men  should 
work  as  closely  together  as  practicable  and  not  even  the 
first  spading  should  be  taken  more  than  a  rod  in  advance 
of  the  tile  laying.  Each  man  should  remove  a  spading, 
moving  backward  at  the  same  time.  The  man  removing 
the  last  spading  should  also  grade  the  bottom.  He  should 
not  step  on  the  finished  bottom  and  no  one  should  stand 
near  the  edge  of  the  trench,  nor  should  wagons  or  material 
of  any  sort  be  permitted  near  the  trench.  The  soil  removed 
from  the  trench  should  be  placed  as  far  back  as  it  con- 
veniently may  be.  The  tile  should  be  laid  at  once  and 
blinded  by  means  of  a  few  inches  of  earth  caved  from  the 
edges  of  the  trench.  If  the  banks  tend  to  cave  off  in 
large  chunks  or  slabs  it  will  be  necessary  to  brace  them 
apart  with  planks  separated  by  stout  cross-pieces  or  trench 
jacks. 

"A  very  troublesome  condition  is  that  in  which  the 
presence  of  a  wet,  pervious  stratum  near  the  bottom  of 
the  trench  causes  a  lateral  and  upward  movement  of 
the  soil  in  the  bottom  of  the  trench.  In  such  a  case  it  is 
necessary  to  provide  a  tight  cribbing  to  shut  out  the  oozing 
material.  It  consists  of  two  heavy  timbers  held  apart 
by  trench  jacks,  behind  which  is  driven  lumber  sheeting 


186 


PRACTICAL  DRAINAGE 


properly  matched  and  beveled  at  the  lower  ends  to  insure 
a  tight  lit.  The  sheeting  may  be  driven  by  means  of  a 
heavy  maul  and  may  be  removed  with  a  three-legged 
derrick  and  a  special  grabhook. 

"If  the  soil  in  the  bottom  of  the  completed  trench  is  so 
soft  that  it  will  not  support  a  man's  weight,  wooden  racks 
or  cradles  should  be  laid  under  the  tile  to  keep  it  in  line 


FIG.  28.  —  DRAINAGE  MACHINE  WITH  THE  DIGGING  WHEEL  ABOVE 
THE  GROUND. 

and  on  grade.  If  conditions  are  exceedingly  bad  it  often 
is  advisable  to  use  sewer  pipe  in  place  of  drain  tile,  as  the 
bells  aid  in  keeping  the  line  intact.  Second  quality  sewer 
pipe  is  suitable  and  generally  may  be  purchased  at  about 
the  same  price  as  drain  tile.  Under  ordinary  conditions, 
however,  the  use  of  sewer  pipe  is  not  recommended,  since 
the  cost  of  freight  and  hauling  is  higher  than  for  drain 
tile  and  it  is  heavier  and  more  difficult  to  handle.  Also, 
in  stable  ground  it  is  necessary  to  dig  out  places  for  the 
bells,  which  considerably  increases  the  cost  of  trenching. 


CONSTRUCTION  METHODS  187 

"Tile  should  be  laid  with  extreme  care.  The  joints 
should  be  as  close  as  possible,  and  if  the  soil  is  semi-fluid 
and  contains  much  fine  sand  and  silt,  it  will  be  necessary 
to  provide  some  means  of  keeping  the  oozing  material 
from  entering  the  tile  joints.  Almost  all  the  water  enter- 
ing tile  lines  makes  its  way  through  the  joints,  practically 
none  entering  through  the  walls  of  even  the  more  porous 


FIG.  29.  —  DRAINAGE  MACHINE  WITH  THE  DIGGING  WHEEL  IN 
THE  TRENCH. 

tile,  so  the  covering  for  the  joints  must  provide  for  the 
ready  passage  of  water.  Straw  makes  a  very  good  filter 
when  new,  but  it  is  likely  to  decompose  and  form  a  sticky, 
impervious  mass  over  the  joints.  Brush  and  willows  are 
not  satisfactory  and  render  any  subsequent  removal  of 
the  tile  very  difficult.  Graded  gravel,  ranging  in  size 
from  sand  to  pebbles  an  inch  in  diameter,  makes  an  ex- 
cellent filter,  but  it  is  not  always  available.  Cinders  also 
are  satisfactory.  Strips  of  burlap  wrapped  about  the 
joints  give  good  service.  The  custom  of  laying  strips  of 
building  paper  over  the  joints  cannot  be  commended, 


188  PRACTICAL  DRAINAGE 

since  the  greatest  tendency  is  for  the  sand  and  silt  to  enter 
at  the  bottom  and  if  paper  is  wrapped  tightly  entirely 
around  the  joints  the  water  itself  will  be  shut  out.  For 
genuine  quicksand,  perhaps  the  best  material  is  cheese- 
cloth, which  should  be  doubled  once  or  twice  and  wrapped 
carefully  about  the  joint.  This  material  soon  decomposes, 
but  in  the  meantime  the  soil  becomes  compacted  so  that 
the  purpose  is  served., 

"The  more  pervious  materials  should  be  placed  adjacent 
to  the  tile.  The  backfilling  may  be  done  with  a  plow 
with  three  or  more  horses  and  a  long  pole  evener,  or  with 
a  scraper,  road  grader,  or  go-devil.  Recently  power 
backfillers  have  been  placed  on  the  market.  All  the  soil 
should  be  returned  to  the  trench  and  be  banked  up  over  it, 
so  that  future  settling  will  not  leave  a  depression  over 
the  drain. 

"In  machine  trenching  it  generally  is  necessary  to  draw 
a  portable  shield  after  the  machine  in  which  the  tile  may 
be  laid  and  blinded  before  caving  takes  place." 

Outlets  and  Silt  Basins.  —  The  efficiency  of  a  drainage 
system  may  be  greatly  lessened  by  an  ineffective  outlet. 
When  the  water  leaves  the  drain  it  should  flow  away 
freely  and  not  be  allowed  to  back  up  in  the  mouth  of  the 
drain,  since  this  condition  causes  silt  to  deposit  and  finally 
clog  the  drain.  The  effectiveness  of  the  drainage  system 
throughout  its  entire  length  may  be  lessened  by  standing 
water  at  the  outlet.  If  the  fall  of  the  land  does  not  per- 
mit of  rapid  flow  from  the  outlet  it  may  be  necessary  to 
let  the  water  run  into  a  pit  and  then  pump  it  out.  This 
method  is  in  successful  operation  at  Kearney  Park,  Cali- 
fornia, in  the  system  described  by  Weir  (13).  Here  the 
pumps  are  turned  on  by  an  automatic  switch  operated 
by  a  float. 


COST  OF   DRAINAGE 


189 


Provisions  should  be  made  to  keep  stock  from  tramping 
on  the  outlet  and  destroying  it.  In  drains  that  are  dry 
part  of  the  time,  screens  to  keep  out  rodents  and  other 
troublesome  animals  should  be  placed  over  the  outlet. 

Manholes  at  intervals  in  the  system  assist  in  locating 
trouble.  These  manholes  may  be  constructed  in  such  a 


FIG.  30.  —  SILT  Box  WITH  LID.    THE  SILT  THAT 
SETTLES  IN  THE  Box  CAN  BE  SPADED  OUT. 

way  that  they  serve  as  silt  basins  and  thus  eliminate 
from  the  system  silt  that  might  clog  the  tile.  These  silt 
basins  are  particularly  necessary  if  the  fall  of  the  drain 
has  to  be  reduced.  A  good  type  of  combination  silt  trap 
and  manhole  is  shown  in  Fig.  30. 

Cost  of  Drainage.  —  The  cost  of  installing  a  drainage 
system  varies  so  much  with  conditions  that  definite  figures 
cannot  be  given.  Hart  (5)  estimates  the  drainage  of 
irrigated  land  to  vary  from  $15  to  $30  with  $20  as  an 


190  PRACTICAL   DRAINAGE 

average.  If  the  land  is.  so  wet  as  to  require  cribbing  of 
the  trench  the  cost  may  run  up  to  $50  an  acre  or  even 
higher.  He  says  that  the  price  of  tile  may  be  figured  at 
about  i  cent  per  inch  of  inside  diameter  for  each  foot  of 
length  for  small  sizes  and  about  2  cents  for  large  sizes. 
Hand  trenching  costs  from  15  to  25  cents  a  linear  foot  for 
six  feet  deep.  Machine  trenching  is  considerably  cheaper 
but  usually  costs  more  than  a  dollar  a  rod.  The  system 
installed  at  Kearney  Park,  California,  with  its  pumping 
system  cost  $59.59  an  acre,  but  since  it  was  to  be  used  for 
experimental  purposes  it  was  permissible  that  it  be  more 
expensive  than  a  system  installed  by  the  farmer  for  strictly 
economic  purposes.  These  figures  must  all  be  revised  to 
meet  post-war  prices. 

REFERENCES 

1.  BATES,  P.  H.,  PHILLIPS,  A.  J.,  and  WIG,  R.J.    Action  of  Salts  in  Alkali 

Water  and  Sea  Water  on  Cements.     U.  S.  Bur.  Standards,  Tech. 
Paper,  No.  12  (1912),  157  pp. 

2.  BROWN,   C.  F.     Farm  Drainage.     A  Manual  of  Instruction.     Utah 

Sta.  Bui.  123  (1913),  pp.  5-55- 

3.  BROWN,  C.  F.,  and  HART,  R.  A.     The  Reclamation  of  Seeped  and 

Alkali  Lands.     Utah  Sta.   Bui.    in    (1910),  pp.   75-91. 

4.  BURKE,  E.,  and  PICKNEY,  R.  M.  The  Destruction  of  Hydraulic  Cements 

by  the  Action  of  Alkali  Salts.    Mont.  Sta.  Bui.  81  (1910),  pp.  41-131. 

5.  HART,  R.  A.     The  Drainage  of  Irrigated  Farms.     U.  S.  D.  A.  Farmers' 

Bui.  805  (1917),  31  pp. 

6.  HEADDEN,  W.   P.     Destruction  of   Concrete  by  Alkali.     Colo.   Sta. 

Bui.  132  (1908),  pp.  3-8. 

7.  JEFFERY,  J.  A.     Textbook  of  Land  Drainage,  502  pp.     (New  York, 

1916.) 

8.  KING.,  F.  H.     Irrigation  and  Drainage,'  502  pp.     (New  York,  1899.) 

9.  MEADE,  R.  K.     Experiments  on  the  Action  of  Various  Substances  on 

Cement  Mortars.     Engin.  Rec.  68  (1913),  pp.  20-21. 

10.  PARSONS,  J.  L.    Land  Drainage,  159  pp.     (New  York,  1915.) 

11.  SIMS,  C.  E.,  and  DIECKMAN,  G.  P.     Investigation  of  the  Effects  of 

Alkali  on  Concrete  Drain  Tile  near  Lake  Park,  Iowa.     Concrete- 
Cement  Age,  6  (1915),  pp.  278-281. 


REFERENCES  191 

12.  STEIK,  KARL.     The  Effect  of  Alkali  upon  Portland  Cement.     Wyo. 

Sta.  Bui.  113  (1917),  pp.  71-122. 

13.  WEIR,   W.   W.     Preliminary   Report  on   Kearney   Vineyard   Experi- 

mental Drain.     Cal.  Sta.  Bui.  273  (1916),  pp.  103-123. 

14.  WIG,  R.  J.,  and  WILLIAMS,  G.  M.     Investigation  on  the  Durability 

of  Cement  Drain  Tile  in  Alkali  Soils.     U.  S.  Bur.  Standards,  Tech. 
Paper,  No.  44  (1915),  56  pp. 

15.  WILLCOCKS,  WM.     Egyptian  Irrigation,  Chapter  VIII,  pp.  229-254. 

(London  and  New  York,  1899.) 

16.  YOKE,  H.  S.     Organization,  Financing,  and  Administration  of  Drain- 

age Districts.     U.  S.  D.  A.  Farmers'  Bui.  815  (1917),  37  pp. 


CHAPTER  XIV 
CROPS  FOR  ALKALI  LAND 

PLANTS  differ  greatly  in  their  resistance  to  alkali.  Certain 
crops,  such  as  the  beet,  will  withstand  very  large  quantities 
and  still  produce  good  yields,  whereas  others,  like  blue- 
grass,  resent  even  comparatively  small  quantities  of  any 
alkali  salt.  It  is  therefore  of  great  importance  to  choose 
the  proper  type  of  plant  for  the  particular  conditions. 

Factors  Affecting  Resistance.  —  Certain  fundamental 
problems  such  as  the  nature  of  the  alkali- resistant  plants, 
the  nature  of  the  soil,  climatic  conditions,  and  economic 
considerations,  should  be  carefully  studied  before  deciding 
finally  on  which  crop  to  plant.  Perhaps  the  first  thing  to 
consider  is  the  difficulty  in  getting  the  plants  started  in 
the  alkali  soil.  Some  of  the  best  crops  for  alkali  resistance 
when  once  started  well,  of  which  alfalfa  and  beets  may 
be  taken  as  examples,  must  be  planted  shallow  and  if  the 
alkali  tends  to  concentrate  at  the  surface  during  their 
tender  seedling  stage,  it  is  very  difficult  to  secure  a  stand. 
If,  however,  the  alkali  can  be  kept  below  the  feeding  zone 
of  such  plants  by  washing  or  in  other  ways  while  they  get 
a  start,  satisfactory  crops  can  be  secured.  As  alkali  is 
not  so  concentrated  when  the  soil  is  kept  well  moistened, 
this  condition  should  be  sought  while  the  plants  are  young. 
Some  varieties  of  each  crop  are  best  suited  to  resist  alkali 
during  the  seedling  stage;  hence  it  is  important  to  choose 
seed  from  successful  crops  on  similar  soils  where  possible. 
The  character  of  the  root  system  of  different  plants 
needs  consideration.  Shallow-rooted  crops,  like  the  cereals 

192 


FACTORS  AFFECTING  RESISTANCE  193 

and  most  cultivated  grasses,  may  fail  to  give  a  satisfactory 
crop  because  the  alkali  tends  to  concentrate  near  the 
surface  if  evaporation  is  active.  This  accumulation  makes 
the  salts  very  strong  throughout  the  feeding  zone  of  the 
plant  and,  therefore,  toxic  even  when  the  total  quantity 
of  salts  in  the  upper  three  or  four  feet  'is  rather  small. 
Deep-rooted  plants,  like  alfalfa  and  trees,  may  penetrate 
the  alkali  strata  by  growing  in  the  upper  soil  while  the 
alkali  is  beneath  and  gradually  feeding  lower  as  the  alkali 
accumulates  at  the  surface.  In  this  way  some  plants  not 
exceptionally  tolerant  may  withstand  what  seem  to  be 
excessive  quantities  when  the  whole  feeding  zone  is  not 
considered.  Where  alfalfa,  cotton,  and  other  deep-rooted 
plants  get  a  good  start  but  encounter  a  strong  alkali 
stratum  at  a  short  distance  below,  these  plants  may  prove 
less  resistant  than  the  cereals  which  may  feed  in  the  upper 
less  alkaline  soil.  The  latter  condition  is  especially  marked 
when  alkali  is  accompanied  by  a  hardpan  or  heavy  clay 
subsoil.  The  same  may  also  be  said  of  soils  that  are  under- 
lain by  a  shallow  water-table,  pasture  or  meadow  grasses 
and  grains  making  much  better  crops  than  the  deeper,  more 
resistant  crops. 

Another  important  factor  is  the  resistance  of  the  plants 
to  reclamation  methods.  A  few  crops,  among  which  are 
alfalfa  after  once  well  started,  sorgo,  rice  and  berseem 
clover,  can  endure  the  frequent  heavy  irrigations  that  may 
accompany  reclamation.  The  best  crop  of  course  depends 
on  the  particular  conditions,  alfalfa  doing  well  with  good 
drainage  but  not  in  a  soil  containing  excessive  quantities 
of  water,  whereas  some  of  the  other  crops  like  sorgo  may 
do  best  where  drainage  is  not  so  good.  During  the  re- 
clamation process  it  is  a  great  aid  to  have  the  land  shaded 
or  cultivated  in  order  to  prevent  alkali  from  rising.  Alfalfa 


194  CROPS  FOR  ALKALI  LAND 

and  other  plants  which  shade  the  soil  during  the  great 
part  of  the  season  are  preferable  to  those  like  grain  which 
leave  the  land  unshaded  during  spring  and  again  during 
fall.  Beets,  fruits,  and  other  crops  that  are  grown  in 
rows  and  require  cultivation  are  useful  because  of  the 
mulching,  which  helps  check  surface  accumulations  of 
alkali.  For  this  purpose  it  is  better  to  have  annual  crops 
which  allow  the  ridges  to  be  leveled  down  occasionally 
than  perennials  which  allow  alkali  to  accumulate  at  the 
top  of  the  ridges  year  after  year  instead  of  being  washed 
out  of  the  soil. 

The  nature  of  the  soil  also  has  some  influence  on  the 
choice  of  crops.  With  a  lifeless  clay  it  is  preferable  to 
grow  some  crop  such  as  rye  rather  than  one  like  beets 
which  requires  considerable  organic  matter  and  much 
working  of  the  soil  to  produce  a  satisfactory  crop.  It  is 
frequently  profitable  to  raise  rye  as  a  green  manure  crop 
to  improve  the  soil  conditions  before  a  more  exacting 
crop  is  grown.  A  soil  without  good  drainage  and  where 
artificial  drainage  is  impractical  may  often  be  planted  to 
some  of  the  more  resistant  forage  or  meadow  grasses  which 
will  endure  water-logged  conditions.  Soils  with  con- 
siderable organic  matter  are  frequently  more  moist  and 
the  alkali  apparently  less  toxic  than  in  the  ordinary  alkali 
soil  so  that  more  profitable  and  less  resistant  crops  may 
prove  best. 

It  is  unfortunate  that  the  most  tolerant  cultivated  crops 
are  not  well  adapted  to  grow  in  the  climate  of  most  parts 
of  the  United  States  where  alkali  is  found.  The  date 
palm,  which  is  perhaps  the  most  tolerant  crop  for  soils 
containing  chloride  and  sulphate  salts,  rice,  cotton,  ber- 
seem  clover,  and  several  other  desirable  crops  are  adapted 
only  to  the  warmer  alkali  regions.  Australian  salt-bush, 


ECONOMIC   FACTORS  AFFECTING  CHOICE    195 

which  withstands  larger  quantities  of  alkali  than  almost 
any  other  desirable  alkali-resistant  plant,  does  not  do  well 
where  winters  are  severe. 

Economic  Factors  Affecting  Choice.  —  After  knowing 
the  relative  tolerance  of  the  various  crops  and  their  adapt- 
ability to  the  particular  conditions,  certain  economic 
considerations  further  modify  the  choice.  With  cheap  lands 
in  some  of  the  grazing  sections,  for  instance,  it  might  be 
preferable  to  plant  the  land  to  some  permanent  grass 
giving  only  a  medium  yield  than  to  use  the  more  resistant 
crops  such  as  sugar-beets  and  other  high-yielding  plants 
which  do  best  under  certain  other  economic  conditions. 
As  a  general  rule,  forage  crops  are  more  suited  to  alkali 
lands  than  crops  in  which  quality  is  more  important. 
Land  in  the  neighborhood  of  large  cities  or  other  places 
where  there  is  a  good  market  for  intensive  crops,  such  as 
the  vegetables  and  fruits,  is  often  more  economically 
planted  to  these  crops  even  though  they  may  be  somewhat 
less  tolerant  of  alkali  than  other  crops. 

The  use  to  be  made  of  the  crops  also  governs  the  choice 
for  alkali  lands.  Grain  crops  will  produce  a  heavy  growth 
of  fairly  good  hay  in  soil  considerably  too  strong  to  give 
satisfactory  yields  of  grain.  Likewise,  although  cotton 
grown  upon  certain  kinds  of  alkali  lands  does  not  give 
the  fine-textured  fiber  so  desirable  in  the  manufacture  of 
the  high-class  cotton  goods,  it  may  produce  a  profitable 
yield  of  the  coarser  grade  suitable  for  other  purposes. 
Sugar-beets  will  produce  excellent  yields  of  roots  on  land 
that  is  high  in  alkali,  but  if  the  quantity  of  salts,  especially 
sodium  chloride,  be  too  large  the  beets  may  be  so  poor  in 
quality  that  they  are  fit  only  for  stock  feed  and  not  for 
sugar-making.  The  quality  of  sugar  cane  and  of  various 
fruits  is  impaired  when  grown  upon  soils  impregnated  with 


196        CROPS  FOR  ALKALI  LAND 

certain  kinds  of  alkali,  but  as  long  as  the  yiqld  is  sufficiently 
high  to  prove  economical  when  used  for  any  purpose  con- 
ditions may  warrant  the  use  of  such  a  crop  in  preference 
to  crops  not  injured  materially  by  the  alkali  but  which 
do  not  fit  economically  into  the  cropping  system. 

Where  the  main  object  is  to  reclaim  land  quickly  and 
put  it  in  condition  for  the  common  crops,  it  is  frequently 
desired  to  green  manure  the  land,  to  get  good  aeration  of 
the  soil,  to  retain  a  mulch,  and  to  keep  all  moisture  moving 
downward.  For  such  purposes  where  the  soil  contains 
salts  in  quantities  so  large  that  most  ordinary  crops  fail, 
sorgo,  rye,  millet,  barley,  rape,  kale,  and  a  few  other  high- 
resistant  crops  which  yield  a  large  quantity  of  dry  matter 
are  used.  When  the  alkali  content  does  not  exceed  about 
5000  parts  per  million  of  white  alkali,  less  resistant  but 
more  desirable  legume  crops  (sweet  clover,  alfalfa,  Canada 
field  peas,  vetch,  and  horse  beans)  should  be  preferred  to 
the  above  crops,  provided  the  seed-bed  can  be  prepared 
so  that  a  good  stand  may  be  secured. 

Tolerance  of  Alkali  by  Various  Crops.  —  In  studying 
the  figures  given  for  the  quantities  of  salts  that  various 
crops  have  been  found  to  endure  safely,  it  should  be  kept 
in  mind  that  the  character  of  the  plants,  feeding  system 
in  relation  to  the  alkali,  and  the  nature  of  the  soil  as  above 
mentioned  will  often  cause  enormous  differences  with  the 
same  plant.  Soil,  moisture,  climate,  and  perhaps  other 
things  will  often  change  the  relative  tolerance  of  the  dif- 
ferent crops  to  some  extent  so  that  slight  differences  in 
tolerance  mean  little  or  nothing.  Unless  otherwise  men- 
tioned, the  salt  as  given  is  understood  to  be  the  proportion 
found  in  the  soil  to  a  depth  of  four  feet.  Although  this 
arbitrary  unit  will  be  misleading  when  the  concentration 
of  the  salts  varies  at  different  depths  in  the  soil,  as  is  often 


FORAGE    CROPS  197 

the  case,  it  is  the  most  satisfactory  method  available  for 
comparing  the  different  crops  as  a  whole.  Not  only  is 
the  root  system  of  most  ordinary  crop  plants  within  the 
four-foot  zone,  but  also  this  is  the  region  where  a  large 
part  of  the  alkali  is  concentrated.  On  most  alkali  la^nds 
the  salts  in  the  first  four  feet  of  soil  may  be  drawn  toward 
the  surface  where  they  will  concentrate. 

Forage  Crops  have  given  more  satisfaction  for  use  on 
rather  strong  alkaline  soils  than  other  cultivated  crops  as 
a  general  rule.  Quality  in  fruit,  vegetable,  sugar,  fiber, 
and  grain  crops  is  frequently  so  impaired  by  alkali  that 
the  crop  is  practically  worthless  for  the  product  ordinarily 
obtained,  but  since  quantity  is  the  chief  requisite  for  forage 
the  crop  serves  its  purpose  when  a  good  yield  is  obtained. 
Leguminous  plants  as  a  family  are  very  sensitive  to  alkali, 
especially  sodium  carbonate.  Hilgard  (12)  states  that 
alkali  even  when  present  in  quantities  as  small  as  200  or 
300  parts  per  million  is  generally  harmful  to  most  of  the 
legumes.  Alfalfa  and  sweet  clover,  especially  the  latter, 
however,  are  among  the  crops  generally  recommended  as 
being  resistant  to  alkali. 

Alfalfa  sometimes  fails  to  give  satisfactory  results  on 
alkali  land  because  it  is  rather  sensitive  in  the  seedling 
stage.  A  good  stand  and  healthful  growth  in  its  first 
stages  are  sometimes  secured  by  driving  the  alkali  below 
the  seed-bed  by  means  of  a  heavy  irrigation.  Hilgard 
places  the  limit  for  unaffected  growth  at  about  1650  parts 
per  million  total  salts,  about  300  parts  per  million  of 
sodium  carbonate,  or  about  1390  parts  per  million  of  sodium 
sulphate.  Kearney  (17)  places  the  highest  successful 
amount  at  4000  parts  per  million  of  white  alkali,  while 
Means  and  'Gardner  (22)  state  that  4000  parts  per  million 
of  white  alkali  caused  young  alfalfa  to  become  sickly  or 


198        CROPS  FOR  ALKALI  LAND 

unhealthy.  It  is  a  very  sensitive  plant  to  black  alkali 
when  in  the  seedling  stage. 

The  limits  for  an  old  stand  of  alfalfa  range  between 
2000  and  7100  parts  per  million  of  total  salts,  according  to 
the  various  authors.  The  lower  of  these  limits  was  for  a 
sandy  soil,  and  Sanchez  (25)  states  that  on  a  loam  soil  a 
higher  concentration  may  successfully  be  withstood.  That 
the  crop  should  produce  a  heavy  mature  crop  on  soil 
containing  7100  parts  per  million,  most  of  which  was 
sodium  chloride,  might  have  been  due  to  the  fact  that  there 
was  standing  water  at  a  depth  of  four  feet  and  that  the 
salt  was  considerably  diluted  by  the  moisture.  Most 
estimates  place  the  limits  between  3000  and  4000  parts 
per  million  of  white  alkali. 

With  black  alkali,  or  sodium  carbonate,  the  observa- 
tions on  old  alfalfa  land  vary  between  300  and  about  900. 
These  differences  are  partly  due  to  the  differences  in  the 
nature  of  the  soil  and  to  the  different  methods  of  determin- 
ing and  expressing  the  results  of  the  analyses.  As  this 
salt  is  generally  found  in  connection  with  other  alkali 
salts  the  limit  can  hardly  be  expected  to  be  a  definite 
quantity  even  in  soils  of  like  character.  Likewise,  the 
quantity  of  sodium  chloride  and  sodium  sulphate  endured 
successfully  vary  through  a  wide  range  modified  by  the 
presence  of  other  salts.  Where  the  salt  was  mostly  sodium 
chloride,  the  variation  assigned  by  the  authorities  ranges 
from  2000  parts  per  million  on  a  sandy  soil  to  7100  parts 
per  million  on  a  loam  soil  well  supplied  with  moisture.  It 
is  probable  that  on  a  loam  soil  handled  so  as  to  protect  it 
from  accumulation  of  alkali  when  the  crop  is  not  shading 
the  ground  and  kept  well  irrigated  will  support  a  satis- 
factory growth  of  alfalfa  when  it  contains  as  much  as  4000 
parts  per  million  of  sodium  chloride.  On  a  sandy  loam 


SWEET    CLOVER  199 

in  Montana  Neill  (23)  reports  a  diminished  yield  where  the 
alkali  content  was  about  4000  parts  per  million,  mostly 
of  sodium  sulphate,  while  Kearney  (17)  places  the  highest 
quantity  under  which  alfalfa  will  succeed  at  6000  of  this 
salt.  Very  few  important  crops  will  grow  with  larger 
quantities  of  these  alkalies  in  the  soil,-  In  most  soils, 
there  is  a  mixture  of  the  salts  in  various  proportions  so 
the  limits  of  the  separate  salts  serve  only  for  general 
purposes.  The  high  resistance  of  alfalfa  may  be  assigned 
to  its  deep  feeding  habits  in  many  cases,  the  feeding  roots 
not  being  in  the  alkali  zone  but  being  in  the  purer  solu- 
tions below. 

Sweet  clover  (Melilotus  alba  and  M.  officinalis)  is  widely 
recommended  for  alkali  lands.  It  is  as  resistant  as  alfalfa 
and  is  often  preferred  to  alfalfa  for  alkali  land.  Coe  (i) 
states  that  it  will  withstand  so  much  black  alkali  that 
salt  grass  is  the  only  other  crop  that  can  compete  with  it 
on  this  kind  of  land.  It  gives  more  satisfaction  than 
alfalfa  on  alkali  lands  which  are  water-logged  or  have  a 
shallow  water-table.  Sweet  clover  is  not  ordinarily  so 
satisfactory  a  forage  crop  as  alfalfa  because  it  is  necessary 
to  reseed  it  every  alternate  year,  whereas  alfalfa  yields 
well  for  years.  It  is  so  difficult  to  secure  a  good  stand 
of  these  crops  under  alkali  conditions  that  it  is  very  de- 
sirable to  have  a  continuous  or  perennial  crop.  Sweet 
clover  is  easier  to  get  started  on  alkali  land  than  alfalfa. 
It  requires  more  care  in  harvesting  because  if  it  is  allowed 
to  grow  too  long  it  acquires  a  disagreeable  flavor  and  it  is 
not  so  readily  eaten  as  alfalfa.  The  few  observations  on 
the  resistance  of  sweet  clover  to  alkali  show  it  to  rank 
about  with  alfalfa,  so  that  other  conditions  being  equal 
alfalfa  is  the  preferable  crop.  However,  on  water-logged 
land  or  where  alfalfa  does  not  thrive  for  other  reasons, 


200        CROPS  FOR  ALKALI  LAND 

and  where  the  crop  is  desired  more  as  a  means  of  reclaiming 
the  land  for  other  crops  in  a  few  years,  sweet  clover  is 
preferable.  It  is  an  excellent  green  manure  to  be  used  in 
upbuilding  alkali  land. 

Other  Clovers.  —  The  only  other  clover  that  has  been 
found  to  do  well  in  the  presence  of  large  quantities  of  alkali 
is  berseem,  or  Egyptian  clover.  It  has  been  found  to 
endure  4000  to  6000  parts  per  million  of  alkali,  mostly 
sodium  chloride,  under  Egyptian  conditions,  but  it  has  not 
been  used  to  any  extent  in  this  country.  It  requires  mild 
winters  and  is  sensitive  to  cold.  In  Egypt  it  finds  favor 
in  reclaiming  alkali  land  because  it  withstands  flooding 
and  an  excessive  water  content  of  the  soil  which  accompany 
reclamation  methods.  Loughridge  (19)  found  the  limit 
for  burr  clover  to  be  about  1130  parts  per  million  of  black 
alkali,  which  is  exceptionally  high  for  this  salt.  Crimson 
clover  and  Birdsfoot  clover  both  withstood  530  parts  per 
million,  and  white  clover  630  parts  per  million  of  black 
alkali  according  to  this  author.  Red  clover  was  not  found 
growing  in  concentrations  greater  than  670  parts  per  million 
of  total  salts. 

Vetch  ( Vicia  saliva  and  V.  mllosd)  has  met  with  consider- 
able favor'  in  certain  districts  because  it  germinates  well 
on  land  which  will  not  give  a  good  stand  of  other  resistant 
crops  without  considerable  trouble.  Kearney  (17)  places 
the  limit  for  good  germination  between  4000  and  6000  parts 
per  million  of  white  alkali,  and  Loughridge  (19)  found  it 
growing  unaffected  in  a  soil  containing  4340  parts  per  mil- 
lion of  total  salts,  160  parts  per  million  sodium  carbonate, 
200  parts  per  million  sodium  chloride,  and  3980  parts  per 
million  of  sodium  sulphate.  It  may  be  used  for  pasture 
or  as  a  green-manuring  crop,  but  since  it  does  not  do  so 
well  under  most  alkali  conditions  and  since  other  crops 


LEGUMES  201 

such  as  sweet  clover  meet  the  conditions  better  it  has 
found  little  use  on  alkali  lands. 

Field  peas  (Pisum  stavium)  are  said  by  Kearney  (17)  to 
germinate  and  produce  normal  seedling  growth  in  the 
presence  of  2000  parts  per  million  of  white  alkali,  mostly 
sodium  sulphate.  He  states  that  a  good  erop  of  peas  can 
be  grown  in  the  presence  of  4000  parts  per  million  of  this 
type  of  alkali,  but  that  this  quantity  is  near  the  upper 
limit  for  the  seedlings  and  consequently  a  poor  stand 
might  be  expected. 

Beans  are  ordinarily  considered  to  be  rather  sensitive 
to  alkali,  but  Kearney  (17)  classifies  broad  beans  as  pro- 
ducing pods  in  the  presence  of  4000  parts  per  million 
of  white  alkali.  They  are  sometimes  grown  as  a  green  ma- 
nure on  alkali  lands  but  have  not  found  much  favor  because 
other  crops  are  better  adapted  both  on  account  of  climatic 
conditions  and  because  other  crops  produce  more  forage. 
The  seed  being  large,  germination  is  better  than  with 
most  legumes,  but  where  the  growing  season  is  not  cool 
the  growth  is  not  satisfactory.  Neill  (23)  considers  2000 
to  4000  parts  per  million  of  alkali,  mostly  sodium  sulphate, 
as  being  too  much  for  the  seedling  stages  of  beans,  but 
states  that  2000  parts  per  million  or  less  will  allow  all 
ordinary  Wyoming  crops  to  do  well. 

A  number  of  other  leguminous  plants,  including  lupines, 
lentil,  esparcet,  and  other  minor  forage  plants,  have  been 
studied  under  alkali  conditions  by  Loughridge  in  Cali- 
fornia (20),  but  none  have  given  promise  of  competing 
with  alfalfa  and  sweet  clover. 

Grasses.  —  True  grasses  are  as  a  family  more  resistant 
than  the  legumes.  Some  of  the  wild  varieties,  such  as  salt 
grass  and  tussock  grass  mentioned  in  Chapter  VI,  rank  as 
the  most  resistant  plants  known.  The  cultivated  grasses 


202        CROPS  FOR  ALKALI  LAND 

are  generally  more  sensitive  than  the  wild  ones.  Observa- 
tions of  the  more  important  meadow  and  pasture  grasses 
have  been  made,  but  the  number  of  different  conditions  or 
combinations  of  salts  under  which. they  have  been  studied 
makes  the  limits  indicated  for  them  of  less  value  than  for 
plants  which  have  had  a  larger  number  of  studies  made 
of  them. 

Timothy  (Phleum  pratens)  is  reported  by  Kearney  (17) 
to  succeed  in  the  presence  of  4000  to  6000  parts  per  mil- 
lion of  white  alkali  and  perhaps  more  where  the  dis- 
tribution of  alkali  is  uniform.  Traphagen  (29)  places  the 
limit  below  10,000  parts  per  million  where  the  salts  are 
mostly  of  the  sulphate  type.  Near  Baker  City,  Oregon  (3) , 
an  average  crop  was  produced  on  land  containing  700  parts 
per  million  of  sodium  carbonate.  Timothy,  like  almost 
all  of  the  grasses,  has  very  small  seed,  and  it  is  very  im- 
portant in  getting  a  stand  with  such  seed  that  the  seedbed 
be  free  from  alkali.  Unless  the  alkali  can  be  washed  out 
of  the  seedbed  until  the  grasses  get  a  good  start,  it  is  al- 
most useless  to  seed  these  crops  on  alkali  land.  Timothy 
can  be  kept  moist  throughout  the  year,  and  because  keep- 
ing the  soil  moist  dilutes  the  alkali  the  growth  is  much 
more  satisfactory  than  where  less  water  is  used. 

Orchard  grass  (Dactylis  glomeratd)  is  probably  a  little 
more  resistant  to  white  alkali  than  timothy.  Kearney  (17) 
places  the  limit  for  successful  growth  between  4000  and 
6000  parts  per  million  for  the  white  type  of  alkali.  In 
California  the  highest  alkali  in  which  it  was  found  growing 
unaffected  was  1 260  parts  per  million  total  salts,  580  parts 
per  million  of  sodium  carbonate,  and  550  parts  per  million 
sodium  sulphate. 

Brome  grass  (Bromus  inermis)  is  one  of  the  most  resistant 
of  the  tame  grasses.  It  has  been  found  (17)  to  grow  un- 


GRASSES  203 

hindered  in  the  presence  of  as  much  as  5000  parts  per  mil- 
lion of  white  alkali  and  to  make  a  good  growth  and  pro- 
duce seed  with  7000  parts  per  million.  In  California  (20) 
it  was  unaffected  with  3170  parts  per  million  of  total  salts, 
630  parts  per  million  of  sodium  carbonate,  230  parts  per 
million  of  sodium  chloride,  or  2230  parts  per  million  of 
sodium  sulphate.  This  is  one  of  the  best  pasture  grasses 
of  the  western  part  of  the  United  States  where  the  land  is 
not  kept  too  wet. 

Red  top  (Agrostis  alba)  has  not  been  tried  extensively 
under  alkali  conditions  but  Kearney  (17)  reports  it  to 
succeed  in  the  presence  of  4000  to  6000  parts  per  million 
of  white  alkali  and  to  do  better  than  timothy  or  orchard 
grass.  It  grows  well  on  excessively  wet  lands,  lands  too 
wet  for  even  timothy,  and  in  such  land  can  probably 
withstand  as  much  alkali  as  any  of  the  important  culti- 
vated grasses. 

Bluegrass  (Poa  pratensis).  —  In  California  bluegrass 
withstood  successfully  670  parts  per  million  of  total  salts, 
380  parts  per  million  sodium  carbonate,  and  220  parts 
per  million  of  sodium  sulphate.  It  is  ordinarily  regarded 
as  very  sensitive  to  alkali  and  this  apparently  shows 
it  to  be  one  of  the  most  tender  tame  grasses.  In  rather 
extensive  tests  made  by  Harris  and  Pittman  (7)  it  was 
found  to  be  the  most  nonresistant  crop  under  investigation. 

Western  wheat  grass  (Agropyron)  may  be  regarded  as  one 
of  the  most  resistant  grasses,  as  it  can  be  grown  success- 
fully upon  soil  containing  at  least  6000  and  8000  parts 
per  million.  It  is  very  difficult  to  get  started  because  of 
low  germination  of  the  seed.  The  lack  of  popularity  is 
partly  due  to  this  difficulty  of  getting  a  start. 

Japanese  wheat  grass  (Agropyron  japonicum)  was  found 
by  Loughridge  in  California  (20)  in  the  presence  of  2330 


204  CROPS   FOR  ALKALI  LAND 

parts  per  million  of  total  salts,  840  parts  per  million  of 
sodium  carbonate,  820  parts  per  million  of  sodium  chloride, 
or  820  parts  per  million  of  sodium  sulphate. 

Rye  grass  is  one  of  the  favorite  grasses  of  Italy  and 
England,  but  it  has  not  met  with  much  favor  in  this  country 
except  in  a  few  places  on  the  Pacific  Coast.  Italian  rye 
grass  (Lolium  italicum)  is  said  by  Kearney  (17)  to  succeed 
in  soil  carrying  6000  to  8000  parts  per  million  of  white 
alkali.  Other  observations  indicate  it  falls  considerably 
below  this  quantity,  however.  Shutt  (26)  found  a  good 
growth  with  1387  parts  per  million  of  total  salts,  900  parts 
per  million  of  which  was  sodium  sulphate,  and  Lough- 
ridge  (20)  places  the  limit  at  1090  parts  per  million  of 
total  salts,  580  parts  per  million  sodium  carbonate,  120 
sodium  chloride,  or  640  parts  per  million  sodium  sulphate. 
The  latter  author  gives  1410  as  the  limit  for  good  growth 
on  English  rye  grass  (Lolium  perenne). 

Fescue,  like  rye  grass,  is  an  important  grass  of  Europe 
but  has  not  been  able  to  compete  with  the  other  forage 
crops  in  this  country.  Kearney  (17)  regards  it  as  more 
resistant  to  alkali  than  most  cultivated  grasses,  the  limit 
being  between  6000  and  8000  parts  per  million  of  white 
alkali.  It  is  hard  to  get  started  and  therefore  rather 
unsatisfactory  where  the  more  profitable  grasses  can  be 
grown.  Observations  by  Loughridge  (20)  indicate  the 
different  varieties  to  resist  from  1190  parts  per  million  to 
2180  parts  per  million  of  total  salts,  up  to  630  parts  per 
million  of  sodium  carbonate  and  up  to  noo  parts  per 
million  of  sodium  sulphate.  Meadow  fescue  (Fescue 
pratensis)  was  found  by  the  latter  to  be  adapted  to  alkali 
land. 

Tall  meadow  oat-grass  (Arrhenatherum  elatins)  is  another 
European  grass  not  grown  to  any  extent  in  this  country, 


GRASSES  205 

but  it  seems  to  withstand  rather  large  quantities  of  alkali. 
Growth  was  unhindered  in  a  soil  containing  5000  parts  per 
million  of  white  alkali  and  a  good  growth  was  found  where 
7000  parts  per  million  were  present  according  to  Kearney 
(17).  He  regards  it  as  about  equal  to  brome  grass  in 
alkali  resistance,  or  slightly  below  western  wheat  grass. 

A  number  of  new  or  minor  grasses  have  been  tried  on 
alkali  lands  in  California,  but  none  of  them  have  proved 
close  competitors  of  the  higher-producing  standard  grasses 
of  the  United  States,  such  as  timothy  and  alfalfa. 

Wild  or  native  grasses  are  frequently  found  growing  on 
soil  which  is  very  high  in  alkali.  These  grasses  seldom  do 
well  in  pastures  or  meadows  and  generally  do  not  produce 
very  large  quantities  of  feed.  Many  of  them  are  hard  to 
get  started  on  new  land;  their  value  is  likely  to  be  mainly 
as  range  grasses  of  poor  pastures  on  highly  alkaline  soil. 

Salt  grass  (Distichlis  spicata)  is  probably  the  most  im- 
portant of  the  native  grasses.  It  occurs  throughout  the 
world  under  a  great  variety  of  conditions.  It  was  observed 
in  the  Bear  River  Valley,  Utah  (16),  growing  on  soil  con- 
taining from  30,000  to  50,000  parts  per  million  of  salts, 
a  large  part  of  which  was  sodium  chloride,  and  yet  it  does 
well  in  soils  containing  practically  no  salt.  It  shows 
hardly  any  preference  for  the  type  of  alkali  nor  the  con- 
centration. It  has  been  found  growing  apparently  unaf- 
fected on  land  charged  with  8516  parts  per  million  of  sodium 
carbonate  (13),  a  quantity  so  great  that  hardly  any  other 
kind  of  vegetation  could  survive.  Of  course  where  the 
nature  of  the  soil  is  unfavorable,  these  large  quantities  of 
salts  would  be  too  great  for  the  plants  to  do  well,  but  most 
alkali  land  does  not  contain  excessive  quantities  of  salts 
for  this  plant.  It  produces  little  seed  so  that  it  is  very 
difficult  to  propagate  artificially  and  it  is  seldom  planted. 


206  CROPS  FOR  ALKALI  LAND 

Blue- stem  grass  (Agropyron  occidentale)  was  found  grow- 
ing in  a  Montana  soil  (29)  containing  in  the  surface  foot 
320  parts  per  million  of  sodium  carbonate,  1649  parts  per 
million  of  sodium  chloride,  and  24,080  parts  per  million 
of  sodium  sulphate.  The  average  for  the  upper  four  feet 
was  384  parts  per  million  of  sodium  carbonate  and  10,360 
parts  per  million  of  sodium  sulphate.  There  was  a  good 
growth  of  mixed  grass,  mainly  blue-stem,  in  this 
meadow  (29). 

Tussock  grass,  or  purple  lop  (Sporobolus  airoides) ,  men- 
tioned in  Chapter  VI  as  an  alkali-indicating  plant,  with- 
stands very  large  quantities  of  alkali.  It  is  relished  by 
stock  but  will  probably  not  do  well  except  on  the  ranges. 

Alkali  meadow-grass  (Puccinellia  airoides)  (24),  also 
mentioned  in  Chapter  VI,  may  furnish  good  browsing 
for  stock  and  if  available  at  the  proper  time  it  may  furnish 
profitable  hay  on  moist  alkali  lands. 

Prairie  grasses  were  observed  by  Shutt  and  Smith  (26) 
in  Canada  to  withstand  700  parts  per  million  of  sodium 
sulphate  in  the  upper  6  inches  of  soil  even  where  the  soil 
beneath  this  held  over  6000  parts  per  million  and  the  upper 
3  feet  averaged  6717  parts  per  million.  Where  the  upper 
6  inches  of  soil  contained  4320  parts  per  million  of  sodium 
sulphate  and  the  average  for  the  upper  3  feet  was  9773 
parts  per  million  of  total  salts,  there  was  a  poor  growth, 
however. 

Modiola  (Modiola  procumbens),  a  weed  introduced  into 
California  from  Chile,  is  reported  by  Loughridge  (20)  to 
withstand  13,100  parts  per  million  of  total  salts,  composed 
of  1190  parts  per  million  sodium  carbonate,  10,210  parts 
per  million  sodium  chloride,  and  1700  parts  per  million  of 
sodium  sulphate  in  the  upper  foot  of  soil.  It  has  been 
found  to  make  an  acceptable  pasture  where  alfalfa  could 


GRASSES  207 

not  be  started  well.  Were  it  not  for  the  fact  that  it  is  a 
troublesome  weed  where  not  wanted,  it  would  probably 
find  more  favor  as  a  pasture  grass. 

Salt-bushes  (A triplex  spp.),  as  noted  in  Chapter  VI, 
make  an  acceptable  forage  where  the  land  is  too  alkaline 
to  permit  successful  growth  of  the  better  "classes  of  forage 
plants.  There  have  been  a  number  of  attempts  to  intro- 
duce these  plants  as  cultivated  crops  for  alkali  land.  The 
Australian  salt-bush  (especially  A.  semibaccatd)  is  said  to 
be  well  adapted  to  California  conditions  and  to  be  easily 
propagated.  Hilgard  (13)  regarded  it  as  being  one  of  the 
most  promising  forage  crops  for  alkali  lands,  being  a  quick- 
growing  and  high- yielding  plant  as  well  as  producing  hay 
which  is  readily  eaten  by  all  animals.  It  is  not  adapted 
to  climates  with  severe  winters  nor  to  places  frequented  by 
summer  fogs.  It  would  be  of  little  value  outside  of  a  mild 
climate.  Other  varieties  of  salt-bushes  have  been  tried  for 
the  more  severe  interior  country  and,  although  where  once 
started,  they  yield  a  fairly  large  quantity  of  good  forage, 
these  plants  have  received  almost  no  recognition  in  a 
practical  way.  They  are  so  difficult  to  get  started  that 
farmers  will  not  take  the  trouble  to  plant  them. 

Giant  rye-grass  (Elymus  condensatus)  is  reported  by 
Hilgard  (12)  as  being  in  about  the  same  class  as  tussock 
grass  for  alkali  resistance  (3000  to  31,000  parts  per  million 
-tussock).  In  its  wild  state  it  grows  in  large  clumps, 
but  where  sown  at  the  rate  of  about  twenty-five  pounds 
per  acre  it  makes  a  rather  uniform  growth  of  coarse  but 
palatable  grass  or  hay  for  sheep  or  cattle.  When  grown 
on  alkali  land  it  generally  contains  considerable  salt  which 
makes  it  somewhat  laxative  for  horses.  Although  it  is 
at  present  not  receiving  much  attention  as  a  cultivated 
crop,  it  should  occupy  more  of  the  soils  containing  too 


208        CROPS  FOR  ALKALI  LAND 

much  alkali  for  alfalfa,  and  similar  crops.  Being  a  large 
yielding  grass,  it  is  grown  as  a  hay  crop  on  some  of  the 
less  desirable  lands  of  Oregon  and  Washington  as  well  as 
a  few  other  places. 

Sedges  and  rushes  frequently  form  the  main  growth  of 
alkali  swamps  or  low  moist  lands.  The  tuber  bulrush 
(Scirpus  paludosus)  is  recommended  by  Nelson  (24)  as 
being  the  best  of  these  plants  for  forage  on  alkali  lands  of 
the  moist  type. 

Millets,  especially  the  stout  rooted  varieties,  are  among 
the  resistant  cultivated  grasses.  Common,  or  foxtail 
millet  (Chaltochloa  italica)  is  classified  by  Kearney  (17) 
as  withstanding  60,00  to  8000  parts  per  million  of  white 
alkali,  a  good  crop  usually  being  secured  where  not  more 
than  the  lower  quantity  is  present  and  a  fair  crop  between 
the  two  points  or  even  a  little  above.  Barnyard  grass 
(Panicum  crus-galli]  resists  white  alkali  fairly  well  ac- 
cording to  Hilgard  (13).  Proso,  or  broom-corn  millets, 
(Panicum  miliaceum)  will  produce  a  good  crop  in  the 
presence  of  less  than  4000  parts  per  million  of  white  alkali, 
but  since  other  crops  are  usually  more  profitable  with  this 
quantity,  and  since  an  excess  of  alkali  is  likely  to  reduce 
the  yield  of  grain  to  an  unprofitable  point,  its  value  on 
such  lands  is  questionable.  Loughridge  (20)  found  Egyp- 
tian millet  (Elusine  coracana)  growing  unaffected  in  the 
presence  of  1140  parts  per  million  of  total  salts,  580  of 
sodium  carbonate,  and  480  of  sodium  sulphate,  and  many- 
flowered  millet  (Milium  multifloruni)  in  the  presence  of 
1090  total  salts,  210  sodium  carbonate,  120  sodium  chloride, 
and  440  parts  per  million  of  sodium  sulphate.  Other  millets 
that  were  tested  resisted  less  than  1000  parts  per  million. 

Sorghums  are  rather  resistant,  can  endure  flooding,  and 
are  readily  cultivated  so  that  they  are  among  the  better 


RAPE  209 

crops  for  reclaiming  alkali  lands.  If  the  soil  can  be  kept 
moist  by  irrigation  while  the  plants  are  in  the  seedling 
stage  the  crop  apparently  does  not  suffer.  Kearney  (17) 
places  the  limit  for  the  saccharine  sorghums  between  6000 
and  8000  parts  per  million  of  white  alkali  or  for  an  almost 
assured  crop  just  below  these  points.  ?He  states  that 
these  sorghums  are  among  the  most  resistant  plants  when 
in  the  seedling  stage.  An  Hawaiian  (5)  experiment  showed 
cane  to  endure  3357  parts  per  million  of  alkali,  mostly 
sodium  chloride,  the  growth  being  unchecked  when  the 
roots  of  the  plants  were  drawing  from  free  water,  but  that 
when  the  moisture  content  of  the  soil  fell  to  28  per  cent 
there  was  no  growth  on  a  soil  containing  1980  parts  per 
million  of  this  salt.  The  highest  quantities  of  alkali  on 
which  Loughridge  (19)  found  sorghum  growing  unaffected 
was  5100  parts  per  million  of  total  salts,  620  parts  per 
million  of  sodium  carbonate,  610  parts  per  million  of 
sodium  chloride,  and  3870  parts  per  million  of  sodium 
sulphate.  These  limits  show  that  where  sorghums  are 
adapted  they  may  be  expected  to  grow  on  soil  too  strongly 
alkaline  to  permit  most  ordinary  crops  to  survive. 

Rape  (Brassica  napus  and  B.  oleracea),  while  practically 
unknown  to  the  farmers  of  the  United  States,  is  a  rather 
alkali-resistant  crop  which  is  extensively  used  for  forage 
in  Europe.  The  seedling  of  this  crop  is  very  delicate  or- 
sensitive  to  alkali  and  there  is  difficulty  with  the  stand 
where  a  crust  is  formed  before  the  plants  break  through 
the  upper  soil.  By  keeping  the  soil  moist  and  paying 
close  attention  to  the  seedlings  little  attention  will  need 
to  be  given  rape  on  account  of  alkali  thereafter.  The 
plants  withstand,  and  make  a  fair  growth  with,  as  much 
as  6ooc  to  8000  parts  per  million  of  white  alkali  and  will 
grow  practically  unchecked  with  4000  parts  per  million, 


210  CROPS   FOR  ALKALI  LAND 

according  to  Kearney  (17).  This  crop  is  not  well  adapted 
to  the  present  economic  conditions  of  the  United  States 
and  it  is  too  troublesome  in  its  seedling  stage  to  gain  popu- 
larity with  the  American  farmer. 

Grain  crops  have  been  tried  under  a  great  variety  of 
alkali  conditions  both  as  a  grain  and  a  forage  crop.  They 
may  successfully  produce  forage  or  green  manure  on  land 
too  strongly  impregnated  with  alkali  to  yield  grain  profit- 
ably. During  hot  weather,  unless  the  moisture  conditions 
are  favorable,  grain  is  likely  to  become  shriveled  and  hard 
where  the  so*  contains  considerable  alkali.  Under  certain 
other  condu.cns  the  alkali  may  cause  the  plants  to  spend 
most  of  their  energy  in  leaf  production  rather  than  seed. 

Wheat  has  been  grown  for  hay  on  land  too  strong  for 
alfalfa  to  either  germinate  or  grow  (27).  According  to 
Kearney  (17),  the  highest  quantity  of  white  alkali  per- 
missible for  the  successful  production  of  wheat  hay  was 
4000  to  6000  parts  per  million,  while  for  a  grain  crop  it 
could  successfully  endure  only  1000  to  4000  parts  per 
million.  The  author  (6),  however,  found  wheat  doing 
moderately  well  as  a  grain  crop  where  the  top  foot  of  soil 
contained  8756  parts  per  million  of  total  salts,  1146  parts 
per  million  of  sodium  carbonate,  1577  parts  per  million  of 
sodium  chloride,  and  5840  parts  per  million  of  sodium 
.sulphate,  the  average  salt  content  of  the  top  four  feet  of 
soil  being  11,829  parts  per  million  of  total  salts,  1121 
parts  per  million  of  sodium  carbonate,  2334  parts  per 
million  of  sodium  chloride,  and  7512  parts  per  million  of 
sodium  sulphate.  These  quantities  are  the  average  of 
determinations  in  four  different  fields  in  different  sections 
of  Utah;  enormous  quantities  of  sulphates  amounting  in 
some  cases  to  20,000  parts  per  million  were  found  in  soil 
growing  wheat,  but  where  sodium  chloride  became  a  promi- 


GRAIN    CROPS 


211 


nent  salt  the  quantity  was  much  less.  Observations  by 
Shutt  and  Smith  (26)  show  that  on  a  loam  soil  with  a 
heavy  clay  subsoil,  wheat  made  a  gdod  growth  where  the 
upper  six  inches  of  soil  contained  practically  no  alkali 
salts,  but  the  next  foot  contained  1780  parts  per  million, 
and  below  this  over  8000  parts  per  million  of  salts  most 
of  which  was  sodium  sulphate.  When  the  upper  six 
inches  contained  1230  parts  per  million  of  salts  and  the 


FIG.  31.  —  ALKALI  SPOT  IN  A  GRAIN  FIELD. 

soil  beneath  this  7000  parts  per  million  the  growth  was 
poor,  apparently  showing  that  the  upper  six  inches  of  soil 
was  the  injurious  portion.  In  the  Bear  River  Valley, 
Utah,  Jensen  and  Strahorn  (16)  found  wheat  doing  well 
in  a  soil  the  top  foot  of  which  contained  5000  to  5600  parts 
per  million  of  alkali,  mostly  sodium  chloride.  Lough- 
ridge  (19)  places  the  limits  for  unaffected  growth  at  1520 
parts  per  million  total  salts  for  Gluten  wheat  and  1080  for 
ordinary  wheat. 

For  sodium  carbonate  Headden  (8)  states  that  400  parts 
ner  million. in  the  soil  will  prove  injurious  to  wheat,  while 


212  CROPS  FOR  ALKALI  LAND 

Jensen  and  Mackie  (15)  place  the  limit  of  profitable  pro- 
duction below  500  parts  per  million.  The  quantity  of 
sodium  chloride  that  may  be  tolerated  without  notable 
injury  to  wheat  has  been  placed  at  from  100  to  about 
5000  parts  per  million  by  the  various  investigators.  Few 
observations  have  been  made  where  sodium  chloride  or 
sodium  sulphate  were  the  main  salts.  Traphagen  (29) 
states  that  the  danger  limit  for  wheat  when  the  salts 
consist  of  sulphates,  two-thirds  sodium  sulphate,  and  the 
rest  magnesium  sulphate  is  about  10,000  parts  per  million. 
Considering  only  the  sodium  sulphate,  this  estimate  is 
nearly  the  same  as  the  figures  of  Shutt  (26)  and  the  au- 
thor (6),  but  much  above  these  of  Loughridge  (19).  It  is 
probable  that  the  great  discrepancies  shown  in  these  ob- 
servations are  partly  due  to  a  number  of  factors  such  as 
the  nature  of  the  soils,  mixtures  of  the  salts,  and  feeding 
zone  of  the  roots.  The  variety  of  grain,  as  indicated  in 
the  seedling  tests  noted  in  Chapter  V,  would  probably 
have  some  influence  but  not  so  much  as  the  figures  indicate. 
Barley  is  the  high-yielding  grain  of  the  West  which 
corresponds  to  corn  in  the  central  states.  It  is  commonly 
looked  upon  as  being  the  most  tolerant  of  the  ordinary 
grains  for  alkali.  A  number  of  observations  have  in- 
dicated that  this  crop  grows  practically  unhindered  with 
2000  to  4000  parts  per  million  of  white  alkali  and  that  it 
frequently  produces  a  good  crop  of  grain  with  as  much  as 
6000  parts  per  million  of  white  alkali  in  the  soil.  When 
grown  as  a  forage  crop,  there  will  be  a  satisfactory  yield 
when  the  soil  contains  from  6000  to  8000  parts  per  million, 
provided  the  seedbed  is  kept  fairly  free  at  first,  according 
to  Kearney  (17).  Jensen  and  Mackie  (15)  found  a  poor 
stand  of  barley  on  soil  containing  500  parts  per  million 
of  sodium  carbonate,  but  Holmes  (14)  states  that  this 


GRAIN    CROPS  213 

quantity  will  be  withstood  fairly  well.  Loughridge  (19) 
found  it  to  do  well  in  the  presence  of  740  parts  per  million 
of  sodium  carbonate.  Although  Dymond  and  Houston  (4) 
state  that  barley  was  growing  on  soil  having  been  flooded 
by  sea  water  and  containing  16,000  to  20,000  parts  per 
million  of  salt  in  the  upper  six  inches  of  soil,  it  is  probable 
that  the  plant  roots  were  not  feeding  in  the  zone  contain- 
ing the  salts.  It  withstands  black  alkali  better  than 
wheat.  The  highest  sodium  chloride  content  of  soil 
that  barley  has  been  observed  to  tolerate  unaffected  was 
640  parts  per  million  in  a  California  soil  (19)  which  also 
contained  other  salts.  Traphagen  (29)  places  10,000 
parts  per  million  of  sulphates  as  the  danger  limit  for 
barley  where  two- thirds  of  this  was  sodium  sulphate. 
Barley  should  be  more  important  as  an  alkali  land  crop. 
Oats  are  generally  considered  to  be  intermediate  between 
wheat  and  barley  in  alkali  resistance.  Kearney's  obser- 
vations (17)  indicate  wheat  and  oats  to  be  about  equal 
in  this  respect,  but  most  others  show  oats  to  be  the  more 
tolerant,  especially  of  sodium  carbonate  and  sodium 
chloride.  The  author  (6)  found  5000  to  10,000  parts  per 
million  of  total  salts  in  the  upper  foot  and  6000  to  8000 
parts  per  million  for  the  average  of  the  top  four  feet  in 
soils  producing  a  medium  crop  of  oats.  Others  indicate 
much  less  than  this  to  have  caused  serious  trouble.  A 
very  wide  difference  is  noted  for  the  effect  of  sodium  car- 
bonate, but  it  appears  that  from  600  to  700  parts  per  mil- 
lion of  this  salt  is  as  much  as  is  safely  withstood.  No 
figures  are  available  for  the  tolerance  of  oats  to  sodium 
chloride  alone  or  where  this  salt  composes  the  main  alkali, 
but  where  much  carbonate  is  present  700  to  1400  is  more 
than  the  crop  can  withstand  safely.  Traphagen  (29) 
places  the  limit  for  sulphates  the  same  for  oats  as  for 
wheat  and  barley. 


214  CROPS  FOR  ALKALI  LAND 

Rye  has  been  highly  recommended  as  a  crop  to  produce 
forage  and  green  manure  for  alkali  lands  too  strong  for 
most  ordinary  crops.  Hansen  (5a)  used  it  with  good  success 
in  reclaiming  land  containing  about  17,100  parts  per  mil- 
lion of  alkali,  mostly  sodium  sulphate,  and  was  able  to  re- 
duce the  alkali  content  of  the  soil  considerably  by  turning 
the  crop  under  as  green  manure.  The  seedbed  for  rye 
should  not  contain  more  than  about  5000  parts  per  million 
of  white  alkali,  however,  or  a  poor  growth  will  result. 
With  rye,  as  with  other  crops  to  be  grown  on  alkali  lands, 
the  quantity  of  seed  sown  should  be  greater  than  for  crops 
on  ordinary  land  and  the  seedbed  made  as  free  from 
salts  as  possible  by  cultural  methods  and  irrigation. 
Kearney  (17)  regards  rye  as  being  about  equal  to  barley 
in  alkali  resistance,  or  withstanding  for  a  successful  grain 
crop  between  4000  and  6000  parts  per  million  of  white 
alkali. 

Corn  has  been  found  (12,  13,  17)  to  fail  on  very  weak 
alkali  soils  and  its  production  on  soils  containing  large 
quantities  of  alkali  is  not  ordinarily  to  be  recommended. 

Rice  has  been  found  to  do  well  in  Egypt  (17)  where 
the  alkali  content  of  the  soil  was  as  high  as  10,000  parts 
per  million,  a  large  part  of  which  was  sodium  chloride, 
but  this  was  under  very  favorable  conditions.  The  soil 
can  be  kept  moist  or  wet  in  growing  rice  so  that  more  alkali 
may  be  present  without  injury  than  where  a  lower  soil 
moisture  content  is  maintained. 

Emmer  is  usually  considered  to  be  about  equal  to  wheat 
in  its  resistance  to  alkali.  Grain  crops  other  than  the 
above  mentioned  have  not  given  promise  on  alkali  lands. 

Sunflowers  were  found  by  Loughridge  (19)  to  endure 
3740  parts  per  million  total  salt  of  which  3290  parts  per 
million  were  sodium  sulphate. 


ROOT  AND   VEGETABLE   CROPS  215 

Root  and  vegetable  crops  often  do  well  on  alkali  lands, 
although  some  are  rather  sensitive  and  some,  such  as 
beets  and  potatoes,  suffer  in  quality  when  excessive  alkali 
is  present. 

Sugar-beets  have  been  found  to  be  one  of  the  most  satis- 
factory crops  grown  on  alkali  lands  in  the.  United  States. 
After  they  are  once  well  started  they  will  endure  enormous 
quantities  of  alkali.  Trouble  is  sometimes  experienced 
in  getting  a  stand  where  the  soil  contains  more  than  2000 
to  3000  parts  per  million  of  white  alkali  or  about  500 
parts  per  million  of  black.  The  quality  of  the  roots  is 
impaired  for  sugar-making  when  the  alkali  consists  of 
sodium  chloride  or  nitrates  in  appreciable  quantities.  In 
alkali  soils,  such  as  those  of  certain  sections  of  Colorado 
and  California  in  which  nitrates  form  an  appreciable 
quantity  of  salts,  the  beets  are  often  over-sized  and  low 
in  sucrose  and  purity  of  the  juices.  Headden  (9)  holds 
that  ordinary  alkali,  essentially  sulphates,  are  not  det- 
rimental, but  even  comparatively  small  quantities  of 
nitrates  cause  injury  to  the  quality  of  the  beets. 

As  sugar-beets,  after  passing  the  delicate  seedling  stage, 
feed  rather  deep  in  the  soil  the  quantity  of  alkali  that  may 
be  present  in  the  surface  of  the  beet  land  may  be  very 
great.  Jensen  and  Strahorn  (16)  found  beets  apparently 
doing  well  in  a  soil,  the  top  foot  of  which  contained  about 
30,000  parts  per  million  of  alkali,  a  large  part  of  which 
was  sodium  chloride.  During  the  earlier  part  of  the  season, 
these  beets  were  barely  able  to  withstand  15,000  parts 
per  million  of  alkali  in  the  upper  foot  even  though  the 
moisture  content  of  the  soil  was  rather  high.  It  is  fre- 
quently possible  to  get  a  stand  of  beets  by  giving  the 
land  a  heavy  irrigation  to  drive  the  alkali  below,  just 
before  planting.  After  getting  started  beets  will  endure 


216  CROPS  FOR  ALKALI  LAND 

and  yield  well  with  4000  to  6000  parts  per  million  of  alkali, 
provided  it  consists  mostly  of  the  white  type.  With 
sodium  carbonate  or  sodium  chloride  composing  a  con- 
siderable portion  of  the  alkali,  however,  the  quantity 
endured  will  be  less.  Beets  will  endure  considerably  more 
sodium  carbonate  than  most  of  the  other  important  crops 
of  western  United  States.  They  have  been  found  doing 
well  on  land  containing  from  500  to  over  700  parts  per 
million  of  this  salt.  Where  the  soil  is  crusted  due  to  the 
action  of  sodium  carbonate,  however,  or  where  it  becomes 
strong  about  the  seedlings,  the  stand  will  be  imperfect  and 
the  yield  poor. 

Sodium  chloride  has  been  found  to  have  a  deleterious 
effect  on  the  quality  of  sugar-beets  and  where  this  con- 
stituent of  alkali  exceeds  400  to  500  parts  per  million  the 
quality  is  likely  to  be  inferior,  although  the  growth  may 
be  excellent.  Beets  will  endure  sodium  chloride  in  the 
soil  in  strengths  of  2000  to  4000  parts  per  million,  but 
they  will  not  be  fit  for  sugar-making  when  grown  on  such 
soils.  Neither  the  quality  nor  the  quantity  of  beets 
produced  in  the  presence  of  4000  to  6000  parts  per  million 
of  sodium  sulphate  is  likely  to  suffer  after  the  plants 
once  get  a  good  start. 

Potatoes  have  not  been  found  to  do  well  on  alkali  land. 
Their  quality  is  usually  poor,  especially  where  part  of  the 
salts  consist  of  sodium  chloride  or  nitrates.  These  salts 
also  seem  to  cause  the  skin  of  the  potato  to  be  poorly 
developed  so  that  the  keeping  quality  of  the  tubers  is 
impaired.  Potatoes  may  be  apparently  doing  well  in 
the  presence  of  as  much  as  2000  to  4000  parts  per  million, 
but  they  are  likely  to  be  watery  and  of  poor  keeping  quality 
when  even  as  much  as  1000  parts  per  million  is  present 
It  is  best  to  plant  crops  other  than  potatoes  on  even  the 
weak  alkali  land. 


ROOT   AND    VEGETABLE    CROPS  217 

Onions  may  be  regarded  as  fairly,  tolerant  of  alkali, 
at  least  in  the  form  of  sodium  carbonate  and  nitrates. 
They  were  observed  (2)  making  a  good  growth  in  a  soil 
containing  4500  to  5700  parts  per  million  of  total  salts, 
a  large  part  of  which  was  calcium  nitrate.  With  white 
alkali,  Kearney  (17)  places  the  limit  as  between  4000  and 
6000  parts  per  million.  Shutt  (26)  found  them  growing 
well  in  a  sandy  loam  soil  containing  1080  parts  per  million 
of  total  salts  of  which  530  parts  per  million  was  sodium 
carbonate  in  the  upper  six  inches,  the  soil  to  a  depth  of 
5  feet  containing  1800  parts  per  million  total  salts  of  which 
1350  parts  per  million  was  sodium  carbonate.  The  highest 
quantity  observed  by  Hilgard  (13)  was  2405  parts  per 
million  of  total  salts. 

Asparagus  is  said  by  Kearney  (17)  to  do  well  in  soil 
containing  as  high  as  6000  parts  per  million  of  white  alkali 
and  to  be  benefited  by  sodium  chloride  when  in  small 
quantities. 

Celery  will  grow  practically  unaffected  where  the  total 
salt  in  the  soil  does  not  amount  to  more  than  about  4000 
parts  per  million  and  is  said  to  withstand  sodium  chloride 
very  well. 

Radishes  were  found  by  Loughridge  (19)  to  be  unaffected 
by  3930  parts  per  million  of  total  salts,  550  parts  per  mil- 
lion of  sodium  carbonate,  or  3240  parts  per  million  of  sodium 
sulphate. 

Other  vegetables  have  not  been  found  to  withstand  alkali 
in  large  quantities.  Sodium  chloride  seems  particularly 
injurious  to  vegetables  such  as  radishes,  carrots,  parsnips, 
and  artichokes,  the  quality  being  very  poor.  The  seeds 
of  most  of  the  vegetables  are  small  and  the  seedlings 
delicate  so  that  vegetable  growing  on  alkali  land  is  very 
hazardous. 


218  CROPS  FOR  ALKALI  LAND 

Fiber  crops  are  not  of  great  importance  in  most  alkali 
sections  of  the  United  States  at  present.  There  are, 
therefore,  few  data  for  these  crops. 

Flax  (Linium  usilatissimum)  is  reported  by  Kearney  (17) 
as  having  produced  a  good  crop  where  the  surface  foot  of 
soil  contained  4000  parts  per  million  of  salts.  "The  pres- 
ence of  an  excessive  quantity  of  salts  in  the  soil  below  the 
first  foot  apparently  had  no  injurious  effect." 

Cotton  is  being  grown  in  parts  of  the  Southwest  where 
considerable  alkali  is  found.  It  has  been  produced  ex- 
tensively under  alkaline  conditions  in  Egypt  where  it  was 
found  to  be  rather  resistant  to  alkali.  The  quality  of 
the  cotton  is  impaired  and  the  production  is  considerably 
reduced  where  the  quantity  of  alkali  is  great.  For  the 
short-staple  varieties  where  quality  is  not  so  important 
the  soil  may  contain  4000  to  6000  parts  per  million  without 
serious  injury,  according  to  Kearney  (17).  As  with  the 
vegetables,  cotton  is  injured  in  quality  more  by  sodium 
chloride  than  the  other  salts.  Like  sugar-beets,  it  is  a 
crop  which  requires  considerable  cultivation  and  it  shades 
the  land  during  its  maturity  so  that  the  cultural  methods 
tend  to  keep  the  alkali  from  concentrating  at  the  surface. 

Trees  and  shrubs  have  been  studied  as  to  alkali  resist- 
ance in  the  United  States  very  little  except  in  California. 
It  is  so  difficult  to  determine  whether  the  death  of  trees 
and  shrubs  is  due  to  alkali  or  to  other  unfavorable  condi- 
tions that  data  of  practical  value  are  almost  unobtainable. 
A  rising  water-table  is  one  of  the  common  conditions  ac- 
companying alkali,  and  as  the  roots  of  trees  and  shrubs 
are  in  undrained  soil  which  might  kill  the  trees  were  no 
alkali  present  at  all,  to  what  extent  the  injury  can  be  as- 
suredly due  to  alkali  is  a  difficult  question.  Where  the 
alkali  is  not  evenly  distributed  the  feeding  zone  of  the 


TREES  AND   SHRUBS  219 

trees  is  so  difficult  to  determine  that  the  resistance  of  trees 
is  a  much  more  uncertain  matter  to  determine  than  it  is 
for  the  smaller  cultures. 

Fruit  trees  and  shrubs  which  might  tolerate  large  quanti- 
ties of  alkali  frequently  do  not  give  satisfaction  because  the 
quality  of  the  fruit  is  injured  by  certain  kinds  of  alkali. 
This  is  especially  true  of  the  more  delicately  flavored 
fruits,  such  as  the  peach.  In  case  there  is  a  very  ap- 
preciable quantity  of  alkali  in  the  soil  it  is  usually  better 
to  grow  the  more  resistant  forage  or  grain  crops  until 
the  land  has  been  reclaimed  for  fruit. 

Date  palms  are  the  most  resistant  of  fruit  trees  and  per- 
haps the  most  resistant  of  cultivated  plants.  They  are 
unfortunately  not  adapted  to  the  alkali  lands  of  the  United 
States  with  the  exception  of  certain  of  the  southwestern 
regions.  The  date  palm  has  been  known  to  grow  in  the 
presence  of  30,000  to  40,000  parts  per  million  of  alkali, 
largely  sodium  chloride.  Where  there  are  layers  of  soil 
containing  only  6000  to  10,000  parts  per  million,  this 
palm  will  produce  abundant  crops  even  where  the  sur- 
rounding or  surface  soil  contains  enormous  quantities  of 
alkali.  There  is  no  apparent  injury  where  the  soil  con- 
tains no  more  than  5000  parts  per  million  of  the  white 
alkali,  although  where  black  alkali  is  encountered  the 
resistance  is  less.  About  600  parts  per  million  of  sodium 
carbonate,  5000  parts  per  million  of  sodium  chloride,  and 
20,000  to  50,000  parts  per  million  sodium  sulphate  have 
been  successfully  withstood.  Palm  groves  are  found 
flourishing  where  the  upper  soil  contains  15,200  parts 
per  million  of  alkali  and  the  surface  of  the  ground  is  white 
with  alkali.  The  quality  of  the  fruit  is  apparently  not 
greatly  impaired  even  where  the  alkali,  which  is  about 
one-half  sodium  chloride,  reaches  a  concentration  of  10,000 
parts  per  million. 


220  CROPS  FOR  ALKALI  LAND 

Grapes,  according  to  the  California  observations,  are 
the  most  resistant  fruit  which  does  well  in  many  of  the 
alkali  sections.  They  were  found  to  grow  well  in  soil 
containing  2860  parts  per  million  of  total  salts,  630  parts 
per  million  of  sodium  carbonate,  770  parts  per  million  of 
sodium  chloride,  or  2550  parts  per  million  of  sodium 
sulphate. 

Olives  were  unaffected  in  a  soil  containing  2520  parts 
per  million  of  total  salts,  180  parts  per  million  of  sodium 
carbonate,  420  parts  per  million  of  sodium  chloride,  or 
1920  parts  per  million  of  sodium  sulphate. 

Other  fruits  tolerated  very  small  quantities  of  salts,  so 
small  that  even  the  mildest  alkali  land  would  cause  trouble. 
Orange,  almond,  fig,  pear,  and  apple  trees  withstood  be- 
tween 1000  and  2000  parts  per  million  most  of  which  was 
sodium  sulphate,  whereas  the  toxic  limit  for  prune,  peach, 
apricot,  lemon,  and  mulberry  trees  was  below  800  parts 
per  million  for  this  type  of  alkali.  Hecke,  De  Greeff, 
and  Heime  (n)  found  that  apricot,  peach,  and  similar 
fruit  trees  did  not  suffer  from  gummosis  when  there  was 
salt  in  the  soil  about  the  trees.  This  would  indicate  that 
small  quantities  of  salt  in  the  soil  would  be  advantageous, 
but  the  quantity  could  not  be  large  enough  to  be  called 
alkali  land  without  causing  injury  at  least  to  the  quality 
of  the  fruit. 

Other  trees  tested  by  California  experimenters  and  which 
withstood  over  1000  parts  per  million  of  total  salts  were 
Kolreuteria  4600  parts  per  million,  Oriental  sycamore 
2670  parts  per  million,  and  eucalyptus  trees  2530  parts 
per  million.  The  former  two  trees  withstood  620  and  200 
parts  per  million  of  black  alkali,  respectively,  and  790 
and  1270  parts  per  million  of  sodium  chloride,  respectively. 
Eucalyptus  trees  will  withstand  very  large  quantities  of 


REFERENCES  221 

white  alkali  and  up  to  about  400  parts  per  million  of  black 
alkali  without  apparent  injury.  Washingtonia  palm  and 
camphor  trees  were  rather  sensitive  to  alkali  even  in  small 
quantities,  especially  of  sodium  carbonate  and  sodium 
chloride. 

As  these  trees  are  adapted  only  to  the  warmer  sections 
with  mild  winters,  they  are  of  little  value  outside  of  the 
Southwest.  For  the  other  sections  certain  of  the  poplars 
or  cottonwoods  are  probably  the  best  adapted  to  alkali 
lands.  Locusts  are  also  likely  to  do  well  where  the  alkali 
is  not  too  strong. 

Plants  recommended  by  Kearney  (17)  as  being  suitable 
for  hedges  and  windbreaks  are  Russian  olive  (Elaeagnus 
songoricd)  (Bernh.)  (Gray,  F.  F.  and  G.)  for  moderate 
alkali,  golden  willow  (probably  Salix  mtellina  aured)  for 
regions  having  severe  winters,  pomegranate  (Punica  gr ana- 
turn],  and  tamarisk  (Tamarix  gallica)  which  are  de- 
cidedly resistant,  for  the  southwestern  alkali  lands,  as 
well  as  certain  of  the  larger  salt-bushes.  A  triplex  breweri 
and  A.  longiformis  are  the  species  especially  recommended 
for  this  purpose. 


REFERENCES 

1.  COE,  H.  S.     Sweet  Glover:  Growing  the  Crop.    U.  S.  D.  A.  Farmers' 

Bui.  797  (1917),  p.  13. 

2.  CONNOR,  S.  D.     Indiana  Soils  containing  an  Excess  of  Soluble  Salts 

Proc.  Ind.  Acad.  Sci.  1916,  pp.  403-404. 

3.  DORSEY,  C.  W.     Alkali  Soils  of  the  United  States.     U.  S.  D.  A.  Bur. 

Soils,  Bui.  35  (1906),  pp.  7-196. 

4.  DYMOND,  T.  S.,  and  HOUSTON,  D.     Salt  Water  Flood  of  November 

29,     1897.     Jour.     Essex     Tech.     Lab.     Vol.     3,     pp.     173-182. 
(Abs.  E.  S.  R.  ii,  pp.  326-327.) 

5.  ECKART,  C.  F.     A  Consideration  of  the  Action  of  Saline  Irrigation 

Water.    Hawaiian  Sugar  Planters'  Sta.  Rpt.  1902. 


222  CROPS  FOR  ALKALI  LAND 

5a.   Hansen,    D.    Crops   on   Alkali    Land,    Huntley    Project,    Montana. 
U.  S.  D.  A.  Bui.  135  (igi4),  19  pp. 

6.  HARRIS,  F.  S.     Soil  Alkali  Studies.     Utah  Sta.  Bui.  145  (1916);  pp.  3- 

21. 

7.  HARRIS,  F.  S.,  and  PLTTMAN,  D.  W.     Relative  Resistance  of  Various 

Crops  to  Alkali.     Utah  Sta.  Bui.  168  (1919),  23  pp. 

8.  HEADDEN,  W.  P.    Alkalis  in  Colorado.     Colo.  Sta.  Bui.  239  (1918). 

58  pp. 

9.  HEADDEN,  W.  P.     Deterioration  in  Quality  of  Sugar-beets  Due  to 

Nitrates  Formed  in  the  Soil.     Colo.  Sta.  Bui.  183  (1912),  179  pp. 

10.  HEADLEY,  F.  B.    The  Work  of  the  Truckee-Carson  Experiment  Farm 

in  1912.     U.  S.  D.  A.  Bur.  PI.  Ind.  Cir.  122  (1913),  pp.  13-23. 

11.  HECKE,  E.  VAN,  et  al.     The  Use  of  Common  Salt  for  the  Prevention 

of  Gummosis  of  Fruit  Trees.     Jour.  Soc.  Agr.  Brabant  et  Hainaut, 
52  (1907),  No.  13,  pp.  366-367.     (Abs.  E.  S.  R.  18,  pp.  948-949.) 

12.  HILGARD,  E.  W.     Salts  Compatible  with  Ordinary  Crops.     Cal.  Sta. 

Bui.  128  (1900),  8  pp. 

13.  HILGARD,  E.  W.     Soils,  pp.  466-481.     (New  York,  1906.) 

14.  HOLMES,  J.   G.     Walla  Walla  District,  Washington.     U.   S.   D.   A. 

Bur.  Soils,  Field  Oper.  (1902),  pp.  722-723. 

15.  JENSEN,  C.  A.,  and  MACKIE,  W.  W.     Soil  Survey  of  the  Baker  City 

Area,  Oregon.     U.  S.  D.  A.  Bur.  Soils,  Field  Oper.  (1903),  pp.  1151- 
1170. 

16.  JENSEN,  C.  A.,  and  STRAHORN,  A.  T.     Soil  Survey  of  the  Bear  River 

Area,  Utah.     U.  S.  D.  A.  Bur.  Soils,  Field  Oper.  (1904),  pp.  1018- 
1019. 

17.  KEARNEY,  T.  H.     Choice  of  Crops  for  Alkali  Land.     U.  S.  D.  A. 

Farmers'  Bui.  446  (1911),  32  pp. 

1 8.  KEARNEY,  T.  H.     Plant  Life  on  Saline  Soils.     Jour.  Wash.  Acad. 

Sci.  vol.  8,  No.  5. 

19.  LOUGHRIDGE,  R.  H.     Tolerance  of  Alkali  by  Various  Cultures.     Cal. 

Sta.  Bui.  133  (1901),  42  pp. 

20.  LOUGHRIDGE,  R.  H.    Tolerance  of  Various  'Crops  ior  Alkali.     Cal. 

Sta.  Rpts.  1895-96,  1896-97,  p.  49. 

21.  MEAD,  C.  E.     Crops  for  Alkali  Soils.     N.  Mex.  Sta.  Bui.  33  (1900), 

PP-  37-39-      • 

22.  MEANS,  T.  H.,  and  GARDNER,  F.  D.    The  Alkali  of  the  Soils.    U.  S. 

D.  A.  Bur.  Soils,  Rpt.  64  (1899)  pp.  56-57. 

23.  NEILL,  N.  P.     Soil  Survey  of  the  Laramie  Area,  Wyoming.     U.  S. 

D.  A.  Bur.  Soils,  Field  Oper.  (1903),  pp.  1092-1093. 

24.  NELSON,   A.     Some   Native   Forage   Plants   for  Alkali    Soils.     Wyo. 

Sta.  Bui.  42  (1899),  45  pp. 

25.  SANCHEZ,  A.  M.     Soil  Survey  of  Provo  Area,  Utah.     U.  S.  D.  A. 

Bur.  Soils,  Field  Oper.  (1903),  p.  1141. 


REFERENCES  223 

26.  SHUTT,  F.  T.,  and  SMITH,  E.  A.    The  Alkali  Content  of  Soils  as  Re- 

lated to  Crop  Growth.     Trans.  Roy.  Soc.  (Canada),  Ser.  Ill  (1918), 
XVII. 

27.  SMITH,  J.  G.     Forage  Plants  for  Cultivation  on  Alkali  Soils.     U.  S. 

D,  A.  Yearbook  (1898),  pp.  535-550. 

28.  TOTTINGHAM,  W.  E.    A  Preliminary  Study  of  the  Influence  of  Chlorides 

on  the  Growth  of  Certain  Agricultural  Plants.     Jour.  Am.  Soc.  Agr. 
ii  (1919),  pp.  1-32. 

29.  TRAPHAGEN,  F.  W.    The  Alkali  Soils  of  Montana.     Mont.  Sta.  Bui. 

54  (1904),  pp.  93-121. 


CHAPTER  XV 
ALKALI  WATER  FOR  IRRIGATION 

ONE  source  of  alkali  trouble  may  be  from  irrigation 
water  which  carries  in  solution  large  quantities  of  soluble 
salts.  Water  passing  over  or  seeping  through  alkali  land 
gradually  dissolves  the  soluble  material  which  it  retains 
in  solution.  Drainage  water  coming  from  land  that  is 
high  in  soluble  salts  should  therefore  be  thoroughly  ex- 
amined before  being  used  for  irrigation. 

Streams  that  flow  through  rock  formations,  such  as  the 
Mancos  shale,  which  contain  large  quantities  of  salts  are 
often  so  strongly  impregnated  that  their  waters  are  rendered 
injurious  for  irrigation.  Springs  or  wells  are  often  found 
containing  sufficient  soluble  salts  to  make  the  use  of  their 
waters  dangerous.  A  limited  quantity  of  alkali  in  the  water 
would  not  be  so  serious  if  it  were  not  for  the  fact  that  the 
land  on  which  it  is  used  may  already  have  sufficient  alkali 
so  that  the  addition  of  any  more  would  make  it  unfit  for 
crops. 

Variation  in  the  original  salt  content  of  the  soil  makes 
it  very  difficult  to  determine  just  how  much  alkali  can  be 
present  in  irrigation  water  before  it  becomes  dangerous. 
Notwithstanding  the  difficulty  of  giving  exact  figures, 
the  problem  is  so  important  that  it  merits  the  most  pro- 
found study.  This  is  realized  when  the  extensive  use  of 
irrigation  water  is  known. 

About  95,000,000  acres  of  land,  or  about  7  per  cent  of 
the  total  area  under  cultivation  in  the  world,  is  farmed 

224 


SOURCES  OF  CONTAMINATION  225 

by  irrigation.  This  area  will  be  greatly  enlarged  in  the 
future.  The  25  or  30  per  cent  of  the  earth's  surface  which 
receives  too  little  rainfall  to  allow  farming  without  ir- 
rigation includes  some  of  the  richest  known  farming  land. 
The  southwestern  parts  of  Africa,  South  America,  and 
Australia;  the  northern  part  of  Africa;  the  northern  and 
western  parts  of  North  America  and  Asia;  and  parts  of 
eastern,  southern,  and  western  Europe  are  all  too  dry  to 
permit  of  successful  farming  without  the  use  of  more  water 
than  falls  naturally  on  the  land.  The  successful  farming 
of  these  areas  is  possible  only  through  irrigation.  There 
is  much  more  land  needing  irrigation  than  there  is  water 
to  supply  the  need.  For  this  reason,  it  is  important  to  be 
able  to  utilize  all  available  water.  Even  water  that  would 
not  be  used  if  sufficient  pure  water  could  be  had  must 
be  utilized.  It  becomes  necessary  therefore  to  know  just 
what  are  the  danger  limits  of  alkali  in  irrigation  water. 
If  the  farming  of  certain  lands  requires  irrigation  with 
water  that  will  render  the  land  unproductive,  it  is  highly 
desirable  to  prevent  the  erection  of  expensive  structures 
for  diverting  the  water  and  laborious  operations  in  bring- 
ing the  land  into  a  state  of  cultivation. 

Sources  of  Contamination.  —  Much  valuable  informa- 
tion has  been  gathered  in  the  past  on  the  different  phases 
of  the  alkali-irrigation-water  problem.  It  has  been  ob- 
served that  most  of  the  contamination  of  irrigation  streams 
is  due  to  seepage  and  drainage  waters  which  find  their 
way  back  into  the  rivers  and  canals.  Observations  by 
the  U..S.  Geological  Survey  and  the  U.  S.  Department  of 
Agriculture  show  that  65  per  cent  of  the  Gila  River 
water  (27)  and  30  to  40  per  cent  of  the  Salt  River  water  (3) 
(32)  found  its  way  back  into  the  rivers  after  being  used 
for  irrigation. 


226  ALKALI  WATER   FOR   IRRIGATION 

Numerous  analyses  of  river  and  canal  waters  show  the 
great  quantities  of  soluble  salts  added  to  the  streams  by 
seepage  water.  In  Colorado,  a  river  increased  in  total 
salts  from  no  parts  per  million  to  1178  parts  per  million 
in  traveling  20  miles  (28);  the  Jordan  River,  Utah,  in  a 
course  of  14  miles  changed  from  890  parts  per  million  total 
salts  to  1970  parts  per  million  (n);  the  Sevier  River, 
Utah  (12),  in  running  from  Junction  to  Sigard,  a  distance 
of  60  miles,  had  its  total  salt  content  increased  from  205 
parts  per  million  to  831  parts  per  million  and  by  the  time 
it  had  reached  Delta,  150  miles  from  Junction,  its  salt 
content  had  reached  1316  parts  per  million;  the  Pecos 
River,  at  Roswell,  New  Mexico,  contained  760  parts  per 
million  total  salts,  and  about  30  miles  below  2020  parts 
per  million  were  found  and  there  were  corresponding  in- 
creases until  at  a  point  about  150  miles  below  the  last- 
mentioned  place,  the  river  contained  over  5000  parts  per 
million  (n)  (8).  These  rivers  all  illustrate  the  amount 
of  contamination  from  seepage  water  that  may  occur  in 
almost  any  river. 

At  places  where  drainage  water  from  strongly  alkali 
soils  empties  into  streams  even  greater  pollution  of  the 
water  may  be  expected.  Water  passing  through  a  soil 
containing  20,000  parts  per  million  of  alkali  in  the  upper 
four  feet  has  been  found  to  contain  over  34,000  parts  per 
million  of  salts  when  it  reached  the  drainage  outlet  (5). 
Such  water  emptying  into  the  bed  of  a  small  stream,  as 
is  frequently  done  during  the  height  of  the  irrigation 
season,  may  make  the  further  use  of  this  water  extremely 
dangerous.  The  water  of  the  Arkansas  River  is  very 
pure  at  Canon  City,  Colorado,  but  it  is  entirely  diverted 
for  irrigation  further  down.  At  a  point  about  120  miles 
below  where  seepage  had  increased  the  stream  to  consider- 


SOURCES    OF    CONTAMINATION 


227 


able  size  again,  it  held  about  2200  parts  per  million  of 
salts  (15). 

Evaporation  from  free  water  surfaces  is  the  direct  cause 
of  the  high  alkali  content  of  certain  irrigation  waters. 
Lake  Tulare,  California,  which  has  no  outlet,  was  once 


FIG.  32.  —  THE  MORE  TENDER  TREES  ARE  BEING  KILLED  WITH 
RISING  ALKALI,  WHILE  ALFALFA  is  STILL  UNAFFECTED. 

considered  a  source  of  irrigation  water.  Due  to  evapora- 
tion its  waters  increased  in  concentration  from  1400  parts 
per  million  in  1880  to  3500  parts  per  million  in  1888,  and 
to  5200  parts  per  million  in  1889  (20).  Irrigation  water 
for  the  Carlsbad  district,  New  Mexico,  is  stored  in  a  large 
reservoir  or  lake  fed  by  the  Pecos  River.  It  was  found 
that  for  several  weeks  in  May  and  June,  1899,  the  evapora- 
tion of  this  water  which  already  contained  between  2000 
and  3000  parts  per  million  of  total  salts,  was  equal  to  over 


228  ALKALI    WATER    FOR    IRRIGATION 

200  second-feet  (n).  The  Gila  River  (18)  was  found  to 
contain  1200  parts  per  million  of  total  salts  on  June  5. 
By  June  23  it  had  risen  to  1546  parts  per  million  and  by 
July  8  to  1921  parts  per  million. 

Water  from  torrential  rains  not  having  time  to  sink  into 
the  ground,  especially  on  rather  impervious  soils,  dissolves 
the  surface  salts  and  carries  them  into  the  streams  below. 
Where  much  alkali  is  concentrated  in  the  upper  soil  and 
surface  of  the  catchment  basin  of  the  rivers,  the  high 
flood  waters  may  become  somewhat  saline.  During  1899 
and  1900,  studies  of  the  Salt  and  Gila  Rivers  of  Arizona 
showed  them  to  contain  more  salts  during  flood  periods, 
caused  by  these  sudden  showers,  than  during  the  low 
stages  when  the  salt  content  might  ordinarily  be  expected 
to  be  highest  (8).  Similarly,  observations  of  the  Pecos 
River  showed  the  first  flood  waters  to  contain  5100  parts 
per  million  of  salts,  whereas  later  it  contained  only  2430 
parts  per  million.  The  Salinas  River,  California,  affords 
another  example  of  this  type  of  concentration  of  salts  (48) . 
It  therefore  cannot  be  safely  stated  that  high  waters  are 
best  for  irrigation  purposes. 

Streams  with  their  beds  running  through  portions  of  an 
alkali  stratum  of  soil  may  become  excessively  alkali. 
Salt  Creek,  Utah,  passes  over  a  part  of  the  bed  of  old  Salt 
Lake  which  contains  large  deposits  of  common  salt.  After 
doing  so,  its  water  was  found  to  contain  2300  parts  per 
million  of  total  salts,  of  which  1629  parts  per  million  are 
common  salt. 

Observed  Toxic  Limits.  —  The  exact  quantity  of  alkali 
which  renders  water  unsuitable  for  irrigation  is  uncertain; 
it  varies  with  the  soil,  the  crop,  the  rainfall,  the  amount  of 
water  used,  the  drainage  conditions,  and  a  number  of  other 
factors. 


OBSERVED   TOXIC  LIMITS  229 

Hilgard  (17)  (19)  states  that  although  685  parts  per  mil- 
lion (40  grains  per  gallon)  of  the  common  alkali  salts  should 
be  the  limit  under  most  conditions,  the  nature  of  the 
salts  will  modify  the  limits  considerably.  As  little  as  342 
parts  per  million  of  sodium  carbonate  has  in  some  instances 
caused  serious  injury  in  three  or  four  years,  while  as  much 
as  2739  parts  per  million  of  the  less  toxic  salts  would  not 
be  harmful.  From  his  work  in  California,  Mackie  (24) 
states  that  where  the  salts  are  principally  bicarbonate 
and  chloride  of  sodium,  irrigation  water  containing  more 
than  600  to  700  parts  per  million  of  salt  should  not  be 
applied  except  to  porous,  well-drained  soils.  Guthrie  (13) 
considers  500  parts  per  million  of  sodium  carbonate  as  a 
tolerable  quantity  of  this  salt  even  when  as  much  as  150 
parts  per  million  of  sodium  chloride  are  also  present. 

Where  the  salts  are  more  of  the  sodium-sulphate  type, 
larger  quantities  are  permissible.  Forbes  (18)  states  that 
with  good  drainage  1000  parts  per  million  of  salts  in  ir- 
rigation water  is  an  objectionable  but  permissible  degree 
of  salinity  for  the  soils  of  the  Salt  River,  Arizona.  In 
the  Pecos  Valley  (26)  2500  parts  per  million  to  3000  parts 
per  million  of  salts  were  considered  the  danger  zone  where 
about  50  per  cent  of  the  salts  in  the  water  were  of  sodium 
—  mostly  sodium  chloride  and  sodium  sulphate.  Good 
drainage  in  the  upper  part  of  the  valley  makes  possible 
the  use  of  water  of  higher  salinity  than  is  possible  in  lower 
parts  of  valleys  where  the  soil  is  heavier  and  likely  to 
contain  more  alkali.  Land,  after  being  irrigated  five 
years  with  water  containing  3900  parts  per  million  of  salts, 
was  abandoned  because  of  the  accumulation  of  alkali  and 
seepage  water. 

Experiments  in  Wyoming  (31)   show  that  where  only 
small  quantities  of  water  are  added,  practically  all  of  the 


230  ALKALI  WATER   FOR   IRRIGATION 

salts  in  the  water  are  retained  by  the  soil.  Large  quanti- 
ties of  water  applied  weekly  or  semi-weekly  kept  the  salts 
moving  downward  continually.  Means  (25)  states  that 
the  Arabs  in  the  Desert  of  Sahara  raise  good  crops  of  dates, 
deciduous  fruits,  and  garden  vegetables  when  irrigated 
with  water  containing  as  high  as  8000  parts  per  million 
of  total  salts,  50  per  cent  of  which  in  some  cases  was  sodium 
chloride.  Such  alkalinity,  however,  would  not  be  per- 
missible except  with  very  resistant  crops  on  light,  sandy, 
or  well-drained  soils  and  where  great  care  is  given  to  keep 
the  water  from  evaporating  and  concentrating  the  salts 
at  the  surface. 

Without  special  attention  to  drainage,  a  California  soil 
irrigated  with  water  containing  766  parts  per  million 
sodium  chloride,  327  parts  per  million  sodium  carbonate, 
and  315  parts  per  million  sulphates  was  proving  injurious 
to  an  orchard  after  three  years  (19).  Impervious  clay 
soils  might  be  injured  with  water  too  weak  in  alkali  to 
have  any  noticeable  effect  on  well-drained  ones,  because 
of  the  cumulative  effect. 

Even  in  a  soil  with  good  drainage  in  Arizona,  it  was 
found  that  when  water  containing  over  1000  parts  per 
million  of  salts,  two-thirds  of  which  was  sodium  chloride, 
was  applied,  50  to  60  per  cent  of  the  salts  added  in  the  water 
were  retained  by  the  soil  or  at  least  never  appeared  in  the 
seepage  water  of  the  district  (8).  Soils  flooded  by  sea 
water  for  6  to  8  hours  were  found  to  contain  2000  parts 
per  million  of  sodium  chloride  in  the  surface  soil  where  un- 
flooded  land  contained  only  100  parts  per  million.  How- 
ever, in  a  drainage  experiment  on  the  Swan  Tract,  Utah, 
an  alkali  soil  containing  less  than  3000  parts  per  million 
of  salts  in  the  upper  4  feet  of  soil,  when  flooded  with  water 
containing  about  1500  parts  per  million  of  salts  yielded 


TYPICAL  ALKALI  WATERS  231 

drainage  water  containing  over  11,000  parts  per  million 
of  salts.  The  applications  of  water  were  large,  sometimes 
as  much  as  16  inches  being  applied  at  one  time,  which 
makes  a  great  difference  in  the  retention  of  the  salts  by  the 
soil  (5).  Hawaiian  experiments  with  water  containing 
2000  parts  per  million  of  salts  show  that'  on  a  moderately 
porous  soil  there  was  very  little  accumulation  of  salt  pro- 
vided occasional  heavy  irrigation  was  given  (4).  Wash- 
ing the  salts  out  of  the  soil  occasionally  with  the  relatively 
pure  winter  and  spring  waters  has  proved  very  beneficial 
to  some  alkali  districts. 

In  semi-arid  sections,  the  salt  content  of  irrigation  water 
may  be  much  higher  than  in  the  arid  without  causing  trouble 
because  the  amount  of  water  necessary  to  supplement  the 
rainfall  is  smaller  and  the  larger  precipitation  washes  the 
salts  out  of  the  soil  much  more  readily.  The  U.  S.  Geo- 
logical Survey  (32)  has  attempted  to  classify  irrigation 
waters  as  good  or  bad  by  use  of  a  formula  based  on  the 
toxicity  of  the  individual  alkali  salts  to  field  crops.  Such 
formulae,  while  instructive  as  to  the  relative  injuriousness 
of  the  waters,  are  subject  to  criticism  because  the  factors 
mentioned  above  modify  the  limits  through  a  wide  range. 
A  formula  to  be  of  much  practical  value  must  consider 
these  factors. 

Composition  of  Typical  Alkali  Waters.  —  To  show  the 
variation  in  the  salt  content  of  some  of  the  principal  streams 
of  the  West,  the  analyses  given  in  Table  XXII  are  pre- 
sented. It  should  be  kept  in  mind  that  these  results  will 
not  hold  strictly  for  different  seasons  and  different  sections 
of  the  stream,  but  they  are  useful  in  gaining  a  general 
idea  of  the  nature  of  the  alkali  in  different  streams. 


232 


ALKALI  WATER  FOR   IRRIGATION 


TABLE  XXII.    ANALYSES  OF  SOME  CHARACTERISTIC  ALKALINE 
RIVER  AND  LAKE  WATERS  or  WESTERN  UNITED  STATES 


Percentage  of  Salts 

Total 
Solids 

Cl 

S04 

ca 

Na 

K 

Ca 

Mg 

SiOz 

P.P.M. 

(July)  Salt  River,  Ariz  

59-4 

9.2 

13-1 

40.7 

i.i 

6-5 

3-3 

3-5 

,391 

(Oct.)  Gila  River,  Ariz  

36.5 

14.6 

12.8 

27.2 

i-5 

9.4 

2-5 

S-i 

,085 

(Oct.)  Colorado  River,  Ariz...  . 

17.4 

35-6 

12.2 

18.2 

2.1 

12.4 

2.8 

2.2 

,045 

(June)  Colorado  River,  Ariz.  .  . 

17-5 

12.5 

28.6 

!3-I 

i-5 

IS-4 

5-i 

5-3 

321 

(Low  water)  Pima  Ditch,  Ariz... 

(a) 

2IO 

Buckeye  Canal  Ariz 

2Q   Q 

7  3 

o  6 

24.  0 

.6 

6.6 

2  O 

2    7 

r\Ty 

1880,  Lake  Tulare,  Cal  

oy-y 

17.4 

/  •«) 
16.9 

V* 

26.5 

^T-*y 
33-5 

1.8 

i-5 

'•V 

1.8 

•  •  / 
•  5 

tyf* 

,360 

1889,  Lake  Tulare,  Cal  

20.3 

20.8 

19-5 

35-8 

2.4 

•3 

•3 

.6 

4,910 

1891,  Lake  Elsinore,  Cal  

:o>) 

i,444 

Salinas  River  at  San  Lorenzo 

Creek  Cal 

II.  7 

48.6 

7.0 

16.7 

T.O 

4e 

A   Q 

.6 

3  680 

Estrella  River  Cal.  . 

/ 

ir.  4 

i^\J.\J 
^O.Q 

/  V 
22.3 

AW.  j              -  ._ 
I7-O 

O 

6  3 

T-'V 

A    7 

2.8 

«S)"°y 
I  1  31 

San  Benito  River,  Cal.  .  

-1-  0  '^T 

13.8 

o    y 

29.0 

*  •  *o 
38.3 

I3-I 

5-4 

o 
6.6 

*T*O 

7-7 

2.6 

•"•>  J-O-1 

936 

Cache  la  Poudre,  2  mi.   above 

Greeley,  Col  

2.5 

60.0 

7-3 

9-8 

•3 

12.3 

6.6 

. 

1,571 

Platte    River    below  Cache  la 

Poudre,  Colo  

3-8 

55-3 

8.8 

I2.O 

•4 

13.2 

4-7 

I,  Oil 

Arkansas  at  Rocky  Ford,  Colo.  . 

4.9 

60.7 

2.6 

14-5 

•3 

12.8 

3-8 

•4 

2,134 

Mill  Creek  (cold  spring),  Mont. 

74 

i7-3 

3S-i 

23-5 

1.4 

IO.I 

2.2 

•  7 

3,747 

Walker  Lake  Nev. 

23  8 

21."? 

17-2 

34  6 

trace 

1  .1 

1.6 

2  4.76 

Pecos  River,  N.  M  

^O 

22.6 

•^  x  *o 

43-7 

*  /  *o 
i-5 

OT"* 

14.0 

.8 

13-4 

3-6 

^,<4-/u 
2,384 

Arkansas  River,  Salt  Fork,  Okla. 

51-3 

8.6 

1.2 

36.7 

1.6 

.6 

5,962 

Cimarron,  north  of  Kingfisher.  . 

53-5 

6.2 

•  7 

38.3 

.2 

.1 

H,392 

Brazo  River,  Texas  

30.9 

25-5 

7-i 

20.8 

•7 

II.  I 

i-7 

2.0 

!,J36 

Rio  Grande  River,  Texas  

21.6 

30.1 

"•5 

I4.8 

.8 

13-7 

3.o 

3-8 

791 

Jordan  River,  Utah  

35-5 

26.5 

2.7 

26.1 

7.6 

i-5 

892 

Utah  Lake,  Utah  

26.9 

30.1 

8-5 

18.3 

1.8 

5-3 

6.9 

2.2 

i,254 

Sevier  River  at  Delta,  Utah.  .  . 

25.0 

24.1 

17.9 

16.4 

5-3 

6-5 

• 

1,316 

Beaver  River,  Utah  

23-8 

25-4 

12.  1 

25-5 

2.8 

1.9 

990 

Malad  River,  Utah  

50.0 

2.9 

4-7 

37-4 

4,395 

Salt  Creek,  Utah  

46.2 

3-6 

12.7 

28.9 

i  '.8 

3-3 

1.6 

2,180 

(a)  47.9%NaCl. 

(b)  16.1%  Na2CO3,  69.0%  NaCl,  Na2SO4,  etc.,   7.1%   CaCO3,  MgCO3 
and  silica. 

No  analyses  of  well  waters  used  for  irrigation  are  pre- 
sented because  well  waters  have  been  found  to  vary  so 
greatly  even  in  short  distances  that  each  well  must  be 
tested  separately.  There  are  certain  large  artesian  basins 


TYPICAL   ALKALI    WATERS 


233 


like  that  of  the  upper  San  Luis  Valley,  Colorado,  —  the 
waters  of  which  all  contain  larger  or  smaller  quantities  of 
sodium  carbonate, —  which  permit  of  rough  classification. 
Irrigation  well  waters  seldom  change  in  composition  as 
do  open  streams  because  the  water  is  not  subject  to  the 
various  factors  causing  fluctuations. 

To  show  the  seasonal  fluctuations  in  the  salt  content  of 
rivers,  analyses  of  the  Salt  and  Gila  Rivers  of  Arizona  (8) 
are  given  in  Tables  XXIII  and  XXIV.  These  are  excep- 
tional variations  but  illustrate  how  little  a  single  analysis 
might  mean.  The  Sevier  River,  Utah,  shows  a  somewhat 
less  fluctuation  because  not  influenced  by  flood  waters. 
This  is  shown  in  Table  XXV  (33). 


TABLE  XXIII.    SEASONAL  VARIATION  IN  SALT  CONTENT  OF  SALT  RIVER, 
ARIZONA,  EXPRESSED  AS  PARTS  SALT  PER  MILLION  OF  WATER 


DATE 

TOTAL 

SALTS 

COMPOSITION  OF  THE  WATERS 

Na 

Cl 

S04 

979 
481 
727 

748 
764 
919 

COs 

Ca 
679 

IO2 
724 

402 

437 
651 

Mg 

K 

SiOs 

206 
ill 
583 

465 
529 
355 

(a)  Aug.  i-Sept.  i,  1899  
(b)  Sept.  2-Sept.  9  1899  .  .  . 

724 

IIOO 

1142 
952 
1026 
1069 
I39i 

122 

183 
274 

309 
327 
407 

279 
315 
441 

409 

437 
594 

154 
802 

117 
H5 
I3i 

174 
233 
279 

284 
292 
328 

129 
141 
109 

153 
123 
112 

(c)  Sept.  lo-Oct.  9,  1899.  . 

(d)  Oct.  lo-Oct.  17,  1899  
(e)  Oct.  i8-Dec.  30,  1899  
(f)  Feb.  ly-May  30,  1900  
(§)  June  i-Aug  4  1900 

(a)  High  and  low  summer  water.     Average  of  four  weekly  composites 
of  samples  taken  daily. 

(b)  Summer  flood  water.     One  weekly  composite  of  daily  sample  taken. 

(c)  High  and  low  summer  waters.     Average  of  four  weekly  composites 
of  daily  samples. 

(d)  Winter  flood  water.    One  composite  of  daily  samples  taken. 

(e)  Low   winter   water.     Average   of   ten  weekly  composites  of   daily 
samples. 

(f)  Low  winter  water.    Average  of  thirteen  weekly  composites  of  daily 
samples. 

(g)  Very  low  summer  water.    Average  of  eight  weekly  composites  of 
daily  samples. 


234 


ALKALI  WATER   FOR   IRRIGATION 


TABLE  XXIV.    SEASONAL  VARIATION  IN  SALT  CONTENT  OF  GILA  RIVER, 
ARIZONA,  EXPRESSED  AS  PARTS  SALT  PER  MILLION  OF  WATER 


DATE 

TOTAL 
SALTS 

COMPOSITION  OF  THE  WATERS 

Na 

Cl 

S04 

COa 

Ca 

Mg 

K 

SiOj 

(a)  Nov.  28,  iSgg-Jan.  18,  1900.  . 
(b)  Feb.  i-Mar.  7,  1900  
(c)  Aug.  i—  Aug.  14,  1900  

1168 
1136 
541 
925 
47i 
1085 

312 
280 

823 
271 

401 
383 
Q^S 

574 
364 

155 

165 

947 
130 
964 
145 

653 
693 

no 
127 

524 
663 
686 
836 
57i 
937 

264 
289 
175 
157 
121 
248 

178 
138 

226 

*5I 

752 
652 

266 
5ii 

(d)  Aug.  i5~Aug.  28,  1900  

(e)  Sept  i-Sept  28  1900  .  .  . 

(f)  Sept  29—  Nov.  5,  1900  

(a)  Low  winter  water.     Average  of  seven  weekly  composites  of  samples 
taken  daily. 

(b)  Low  winter  water.     Average  of  five  weekly  composites  of  samples 
taken  daily. 

(c)  Summer  flood  water.     Average  of  two  weekly  composites  of  daily 
samples. 

(d)  Summer  low  water.    Average  of   two  weekly  composites  of  daily 
samples. 

(e)  Summer  flood  water.     Average  of  four  weekly  composites  of  daily 
samples. 

(f)  Summer  low  water.     Average  of  five  weekly  composites  of  daily 
samples. 


TABLE  XXV.     SEASONAL  VARIATION  IN  SALT  CONTENT  OF  SEVIER  RIVER, 
UTAH,  EXPRESSED  AS  PARTS  SALT  PER  MILLION  OF  WATER 


COMPOSITION  OF  THE  WATERS 

TOTAL 

SALTS 

Ca 

Mg 

SO4 

K 

Cl 

HCOs 

NN 

Tulv  20  . 

9^8 

74 

IOO 

222 

10 

58 

278 

1  .7 

August  1  2 

1104 

84 

87 

272 

12 

9° 

290 

1.6 

August  24  

1268 

82 

87 

288 

8 

H5 

284 

I  .-I 

September  18  

1190 

92 

79 

256 

10 

IOI 

292 

i-7 

September  21.... 

1426 

86 

83 

329 

4 

221 

264 

•  4 

October  5  

1406 

74 

75 

328 

4 

210 

249 

,8 

October  19  

1436 

84 

74 

334 

ii 

223 

284 

•9 

November  9  

1376 

84 

74 

326 

10 

204 

290 

9 

Factors  Modifying  Toxic  Limits  of  Salt.  —  Under  or- 
dinary conditions  irrigation  by  the  flooding  method  with 


TOXIC  LIMITS  OF   SALTS  235 

saline  water  has  been  found  better  than  by  the  furrow 
method.  This  is  especially  the  case  where  such  good 
drainage  prevails  that  large  quantities  of  water  may  be 
applied  to  leach  out  any  accumulation  of  salts.  Experi- 
ments have  shown  that  land  flooded  every  8  days  with 
alkali  water  contained  less  than  one-third  the  quantity 
of  alkali  found  in  the  temporary  ridges  under  furrow  ir- 
rigation and  about  27  per  cent  of  that  found  in  unculti- 
vated tree  rows. 

Hawaiian  experiments  (7)  show  that  with  large  applica- 
tions of  water  containing  about  3430  parts  per  million 
(200  grains  per  gallon)  of  common  salt,  large  quantities 
of  lime,  magnesia,  and  potash  are  rendered  available. 
Excessive  irrigations  to  prevent  the  alkali  from  accumulat- 
ing at  the  surface  washed  out  large  quantities  of  lime  and 
magnesia.  Soils  not  well  supplied  with  lime  are  injured 
much  more  by  alkali  than  those  well  supplied.  It  was 
found  in  Wyoming  (31)  that  alkali  irrigation  water  caused 
a  considerable  loss  of  calcium  sulphate  and  calcium  car- 
bonate from  the  soil.  Experiments  in  Oregon  (i)  show 
that  calcium  carbonates  and  nitrates  wash  out  of  the  soil 
faster  than  supplied  in  the  irrigation  water. 

It  has  been  found  in  some  regions  that  the  dissolving 
action  of  alkali  —  the  chloride  and  sulphate  salts  —  on 
lime  destroys  the  impervious  hardpan  layer  often  found 
a  foot  or  two  beneath  the  surface,  thus  allowing  drainage 
to  go  on  more  freely. 

In  the  Southwest,  especially  in  New  Mexico,  certain  of 
the  streams  carry  calcium  sulphate  in  solution  some  of 
the  time.  The  salt  neutralizes  and  makes  less  toxic  the 
sodium  carbonate  found  at  times  in  the  soils  of  the  district. 
If  but  little  or  no  black  alkali  is  present,  as  is  the  case  in 
that  of  the  Pecos  River  irrigation  water  may  contain 


236          ALKALI  WATER  FOR  IRRIGATION 

much  larger  quantities  of  total  salts  than  would  other- 
wise be  permissible.  On  soils  where  an  impenetrable 
hardpan  exists,  sometimes  caused  by  sodium  carbonate, 
the  permissible  salinity  is  generally  lower  than  without 
such  a  condition. 

During  dry  years,  a  single  irrigation  with  alkali  water 
may  mean  the  difference  between  a  crop  and  a  failure, 
provided  the  crop  can  withstand  the  alkali  in  the  water. 
The  limits  in  such  cases  might  be  much  higher  than  in 
cases  where  it  is  necessary  to  irrigate  frequently.  On  a 
clay  loam  soil  containing  a  medium  quantity  of  alkali  in 
the  Bear  River  Valley,  Utah,  the  use  of  irrigation  water 
containing  4395  parts  per  million  of  total  salts,  3625  parts 
per  million  of  which  was  sodium  chloride,  caused  almost 
immediate  wilting  or  death  of  grain.  In  the  Carlsbad 
district,  New  Mexico  (26),  water  containing  4352  parts 
per  million  total  salts  consisting  of  1682  parts  per  mil- 
lion sodium  chloride  and  600  parts  per  million  sodium 
sulphate  injured  young  sugar-beets  when  freely  applied. 

In  Europe  (37)  the  use  of  irrigation  water  containing 
5000  to  10,000  parts  per  million  of  salt  caused  dwarfing 
of  the  better  grasses  and  legumes  so  that  the  yield  was 
considerably  reduced.  Seedling  grass  was  killed  with 
these  concentrations  and  even  500  to  1000  parts  per  mil- 
lion injured  the  stand. 

Corn  (2)  suffered  during  its  vegetative  period  when 
irrigated  with  chloride  and  carbonate  waters  in  concen- 
trations as  high  as  7389  parts  per  million,  but  tomatoes 
did  not.  Sugar  cane  (6)  (7),  when  irrigated  with  pure 
water,  yielded  n  tons  more  sugar  per  acre  than  when  ir- 
rigated with  water  containing  3430  parts  per  million  of 
salts.  The  density  of  the  cane  juice  was  lowered  and  the 
salt  content  raised  by  the  use  of  the  alkali  water  so  that 


REFERENCES  237 

the  purity  of  the  juices  and  the  quantity  present  was  re- 
duced. In  these  experiments  6.75  and  8.79  acre-feet  of 
water  were  applied  during  the  season  and  occasional  heavy 
irrigations  were  given  to  keep  the  salts  from  accumulating. 
When  the  quantity  of  water  used  was  reduced  considerably 
so  that  the  strength  of  the  soil  solution  became  high  such 
a  large  quantity  of  alkali  proved  fatal  (6)  (7). 

Using  coffee,  cocoa,  and  other  plants  to  determine  the 
concentration  of  water  that  may  be  used  with  safety  (22), 
it  was  found  that  the  limits  were  between  5000  and  15,000 
parts  per  million  although  the  result  were  somewhat 
complicated  by  rainfall. 

From  a  survey  of  a  number  of  localities  along  the 
Potomac  River,  Scofield  (30)  assumes  that  the  salt  water 
limit  for  wild  rice  is  about  1754  parts  per  million  (0.03 
normal)  for  sodium  chloride.  The  growth  was  just  about 
proportionate  to  the  strength  of  the  solution  when  less 
than  this  amount  was  present. 

Water  to  be  used  in  irrigating  rice  should  never  contain 
more  than  3000  parts  per  million  of  salt,  according  to 
Fraps  (9)  of  Texas. 

Harris  and  Butt  (14),  after  a  rather  extensive  study  of 
the  use  of  alkali  water  for  irrigation,  concluded  that  under 
average  conditions  more  than  500  parts  per  million  of 
sodium  carbonate,  1000  parts  per  million  of  sodium  chlo- 
ride, 4000  parts  per  million  of  sodium  sulphate,  and  4000 
parts  per  million  of  the  ordinary  mixture  of  salts  are 
dangerous.  In  case  there  were  no  drainage  from  the  land, 
lower  limits  than  those  mentioned  would  have  to  be  used. 

REFERENCES 

i.  ALLEN,  R.  W.  Work  of  the  Umatilla  Reclamation  Project  Experi- 
ment Farm  in  1915  and  1916.  U.  S.  D.  A.  Bur.  PI.  Ind.,  W.  I.  A. 
Circ.  17,  p.  17. 


238  ALKALI  WATER  FOR  IRRIGATION 

2.  BORDIGA,  O.     Irrigation  Experiments  with  Brackish  Water.     Intrn. 

Inst.  Agr.  (Rome),  Mo.  Bui.  Agr.  Intel,  and  Plant  Dis.  4  (1913), 
No.  8.  (Abs.  E.  S.  R.  30,  p.  886.) 

3.  CODE,  W.  W.     Irrigation  in  the  Salt  River  Valley  (Arizona).     U.  S. 

D.  A.,  O.  E.  S.  13ul.  104  (1902),  p.  555. 

4.  CRAWLEY,  J.  T.     Water-holding   Power  and  Irrigation  of  Hawaiian 

Soils.  The  Application  of  Nitrate  of  Soda;  the  Accumulation  of 
Salt  in  Hawaiian  Soils.  Hawaiian  Planters'  Mo.  21  (1902),  No.  8, 
PP-  358-363-  (Abs.  E.  S.  R.  14,  p.  555.) 

5.  DORSEY,  D.  W.     Alkali  Soils  of  the  United  States.     U.  S.  D.  A.  Bur. 

of  Soils,  Bui.  35  (1906),  196  pp. 

6.  ECKART,  C.  F.     Recent  Experiments  with  Saline  Irrigation.     Hawaiian 

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7.  ECKART,  C.  F.     A  Consideration  of  the  Action  of  Saline  Irrigation 

Water.  Hawaiian  Sugar  Planters'  Sta.  Rpt.  (1902),  pp.  24-74, 
76-100;  Rpt.  (1903),  pp.  37-41- 

8.  FORBES,   R.   H.     The  River   Irrigating  Waters  of   Arizona — Their 

Character  and  Effects.      Ariz.  Sta.  Bui.  44  (1902),  pp.  145-214. 

9.  FRAPS,  G.  S.,  The  Effect  of  Salt  Water  on  Rice.      Tex.   Sta.  Bui. 

122  (1909),  6  pp. 

10.  FULAYKOV,  N.,  and  KOSSOVICH,  P.     The  Soils  of  the  Muganj  Steppe 

and  Their  Transformation  into  Alkali  Lands  by  Irrigation.  Ann. 
Inst.  Agron.  (Moscow),  12  (1906),  pp.  27-255.  (Abs.  E.  S.  R.  18, 
p.  818.) 

11.  GARDNER,  F.  D.     A  Soil  Survey  in  Salt  Lake  Valley,  Utah.     U.  S. 

D.  A.  Bur.  of  Soils,  Rpt.  64,  pp.  77-114. 

12.  GREAVES,  J.  E.,  and  HIRST,  C.  T.     Composition  of  the  Irrigation 

Waters  of  Utah.     Utah.  Sta.  Bui.  163  (1918),  43  pp. 

13.  GUTHRIE,   F.   B.     Water  on   the  Farm.     New  South  Wales,  Dept. 

Agr.  Farmers'  Bui.  121,  42  pp.  (1918). 

14.  HARRIS,  F.  S.,  and  BUTT,  N.  I.    The  Use  of  Alkali  Wrater  for  Irriga- 

tion.    Utah  Sta.  Bui.  169  (1919). 

15.  HEADDEN,  W.  P.    A  Soil  Study,  IV.    The  Ground  Water.     Colo. 

Sta.  Bui.  72  (1902),  47  pp. 

16.  HEADDEN,  W.  P.     The  Waters  of  the  Rio  Grande.     Colo.  Sta.  Bui. 

230  (1917),  pp.  3-62. 

17.  HILGARD,  E.  W.     The  Quality  of  Irrigation  Water  in  the  Great  Valley, 

California.     Cal.  Sta.  Rpt.  1890,  pp.  4-56. 

18.  HILGARD,  E.  W.     Quality  of  Irrigation  Water,  pp.  246-251.     (Soils, 

New  York,  1906.) 

19.  HILGARD,  E.  W.     The  Use  of  Saline  and  Alkali  Waters  in  Irrigation. 

Cal.  Sta.  Rpt.  1897-98,  pp.  99-117. 

20.  HILGARD,  E.  W.     The  Lakes  of  the  San  Joaquin  Valley.     Cal.  Sta. 

Bui.  82   (1889),  4  pp. 


REFERENCES  239 

21.  JENSON,  C.  A.,  and  STRAHORN,  A.  T.     Soil  Survey  of  the  Bear  River 

Area,  Utah.     U.  S.  D.  A.  Bur.  of  Soils,  Field  Oper.  (1904),  pp.  995- 
1020. 

22.  KUIJPER,  J.     Effects  of  Using  Salt  Solutions  for  Watering  and  Sprin- 

kling Plants.     Dept.  Landb.  Suriname  Bui.  28  (1912),  pp.  25-31. 
(Abs.  E.  S.  R.  29,  p.  218.) 

23.  LIPPINCOTT,  J.  B.     Storage  of  Water  on  Gila  River,  Arizona.     U.  S. 

Geol.  Survey,  Water  Supply  Paper  33,  p.  24. 

24.  MACKIE,  W.  W.     Reclamation  of  White  Ash  Lands  Affected  with 

Alkali  at  Fresno,  California.     U.  S.  D.  A.  Bur.  of  Soils,  Bui.  42 
(1907),  p.  32. 

25.  MEANS,  T.  H.     The  Use  of  Alkaline  and  Saline  Waters  for  Irrigation. 

U.  S.  D.  A.  Bur.  of  Soils,  Cir.  10  (1903),  4  pp. 

26.  MEANS,  T.  H.,  and  GARDNER,  F.  D.     A  Soil  Survey  of  the  Pecos  Valley, 

New  Mexico.     U.  S.  D.  A.  Bur.  of  Soils,  Rpt.  64,  pp.  36-76. 

27.  NEWELL,  F.  H.     Stream  Measurements  for  1898.     U.  S.  Geol.  Survey, 

Ann.  Rpt.  1899-1900,  Pt.  IV,  pp.  343~347- 

28.  O'BRINE,  D.     Alkali  Soils  of  Colorado.     Colo.   Sta.   Bui.  9   (1889), 

pp.   22-23. 

29.  OTTO,  R.    The  Effect  of  Salt  Water  on  Plants.     Ztschr.  Pflanzenkrank, 

14  (1904),  No.  3,  pp.  136-140.     (Abs.  E.  S.  R.  16,  951.) 

30.  SCOFIELD,  C.  S.     The  Salt  Water  Limits  of  Wild  Rice.     U.  S.  D.  A. 

Bur.  PI.  Ind.  Bui.  72  (1905),  pp.  9-14. 

31.  SLOSSON,  E.  E.     Water  Analyses.    Wyo.  Sta.  Bui.  24  (1895),  pp.  99- 

141. 

32.  STABLER,  H.     Irrigation  Waters.     U.  S.  Geo.  Survey,  Water  Supply 

Paper  274,  pp.  177-181. 

33.  STEWART,  ROBERT,  and  HIRST,  C.  T.     The  Alkali  Content  of  Irriga- 

tion Water.    Utah  Sta.  Bui.  147  (1916),  p.  13. 

34.  VAN  WINKLE,  W.,  and  EATON,  F.  M.    Quality  of  the  Surface  Waters 

of  California.     U.  S.  Geol.  Survey,  Water  Supply  Paper  237. 

35.  WIDTSOE,  J.  A.     Irrigation  Practice,  pp.  77,  84.     (New  York,  1914.) 

36.  WILLCOCKS,  W.    The  Nile  in  1904,  p.  63.     (London  and  New  York, 

1904.) 

37.  WOHLTMAN,   F.    The   Effect   of   Salt   Water  on   Cultivated   Plants. 

Fuhling's   Landw.    Ztg.    45    (1896),  No.   15,  pp.    155-159.     (Abs. 
E.  S.  R.  7,  p.  680.) 


CHAPTER  XVI 
JUDGING   ALKALI  LAND 

A  KNOWLEDGE  of  the  physical  phases  of  alkali  is  not 
sufficient;  the  economic  questions  in  connection  with  it 
must  also  be  given  consideration.  Alkali  has  no  special 
practical  interest  except  in  its  relation  to  the  soil,  which 
it  may  render  entirely  worthless  if  present  in  certain  forms 
and  in  sufficient  concentration.  In  its  less  injurious  forms 
and  at  low  concentrations  it  may  reduce  the  value  of  the 
land  but  slightly.  It  is  important,  therefore,  to  be  able 
to  judge  the  extent  of  reduction  in  value  of  land  due  to  the 
presence  of  alkali.  Many  tracts  have  been  settled,  and, 
after  the  expenditure  of  large  sums  of  money,  abandoned. 
This  loss  might  have  been  saved  had  a  proper  examina- 
tion of  the  soil  been  made. 

Geology  of  Region.  —  In  regions  free  from  alkali  no 
particular  attention  need  be  given  to  it  in  judging  land, 
but  in  regions  where  alkali  is  known  to  exist,  it  must  be 
kept  constantly  in  mind  by  prospective  purchasers  of  land. 
Since  practically  all  of  the  arid  parts  of  the  world  have 
more  or  less  alkali,  the  ability  to  judge  alkali  land  is  very 
important.  One  of  the  first  steps  is  to  look  into  the  origin 
of  the  soil  to  see  if  it  came  from  geological  formations 
that  are  high  in  soluble  salts.  Soils  derived  from  sand- 
stones and  shales  of  certain  formations  are  practically 
always  so  highly  charged  with  salts  that  crop  production 
is  difficult  until  the  salts  are  leached  out.  A  soil  coming 
from  a  formation  of  this  kind,  even  though  it  has  a  salt 

240 


GEOLOGY   OF   REGION 


241 


content  similar  to  that  of  a  soil  from  a  limestone  forma- 
tion, should  be  regarded  with  greater  suspicion  than  the 
latter  soil  because  of  the  possible  recontamination  from 


~] 


FIG.  33.  —  A  LAYER  OF  ALKALI  SEVERAL  FEET  BELOW  THE 
SURFACE.  THE  POSSIBILITY  OF  SUCH  A  LAYER  MAKES  AN 
ANALYSIS  OF  THE  SOIL  NECESSARY  BEFORE  IT  CAN  BE 
PROPERLY  JUDGED. 

the  unlimited  supply  of  salt  in  the  country  rock.  A  knowl- 
edge of  the  geology  of  a  region,  therefore,  is  a  valuable 
supplement  to  other  information  in  judging  alkali  land. 


242  JUDGING  ALKALI  LAND 

General  Appearance.  —  One  who  is  familiar  with  alkali 
can  tell  a  great  deal  by  the  general  appearances  of  the  land. 
The  presence  of  surface  accumulations  of  salts,  the  nature 
of  the  crust,  the  general  condition  and  kind  of  vegetation, 
the  appearance  of  the  subsoil  in  cuts  and  excavations,  the 
slope  of  the  surface,  the  soil  texture  and  structure,  and 
numerous  other  general  appearances  are  helpful  in  judging 
alkali  conditions..  These  superficial  observations,  however, 
must  not  be  relied  on  completely.  For  example,  a  soil 
having  a  high  gypsum  content  and  being  free  from  the 
highly  soluble  salts  may,  through  constant  evaporation 
of  water  at  the  surface,  cause  the  soil  to  be  covered  com- 
pletely with  white  powdery  crystals  which  would  seem  to 
indicate  a  serious  alkali  condition.  Land  of  this  character 
could  easily  be  undervalued  since  the  gypsum  is  not  suf- 
ficiently soluble  to  cause  injury  to  vegetation  and  its 
presence  might  not  be  undesirable. 

On  the  other  hand,  a  soil  may  show  very  little  surface 
indication  of  alkali;  it  may  contain  a  good  growth  of  certain 
kinds  of  vegetation;  yet  an  analysis  might  show  that  at 
some  distance  below  the  surface  there  is  a  layer  of  soil 
that  is  highly  charged  with  salts.  This  land  would  only 
need  to  be  brought  under  cultivation  and  irrigated  to  make 
the  subsoil  alkali  a  real  source  of  danger.  Appearances 
are  helpful,  but  alone  they  are  not  sufficient. 

Native  Vegetation.  —  As  already  discussed  in  con- 
siderable detail  in  Chapter  VI,  the  native  vegetation  is 
one  of  the  most  valuable  indicators  of  the  presence  of 
dangerous  quantities  of  alkali.  It  is  probably  the  best 
single  means  of  judging  alkali  land.  Certain  plants 
such  as  sagebrush  (Artemesia  tridentata)  do  not  live  in 
the  presence  of  high  concentrations  of  salts  and  where 
these  plants  are  found  growing  vigorously  the  land  may 


ANALYSIS  OF  THE   SOIL  243 

be  considered  to  be  comparatively  free  from  alkali.  Certain 
other  plants  such  as  salt  grass  (Distichlis  spicatd)  are  sel- 
dom found  except  on  land  highly  charged  with  salt,  and 
where  found  the  soil  should  be  thoroughly  investigated 
before  an  attempt  is  made  to  use  it  for  agriculture.  Since 
this  question  has  already  been  so  fully  discussed,  no  de- 
tails will  be  given  here.  Chapter  VI  should  be  consulted 
for  further  information. 

The  Water-table.  —  Alkali  lands  are  often  wet.  Sur- 
face accumulations  of  salt  usually  result  from  a  rapid 
evaporation  of  water  which  rises  from  a  water- table  that 
is  comparatively  near  the  surface.  There  are  soils  high 
in  alkali  with  a  water-table  hundreds  of  feet  below  the 
surface.  In  these  soils  the  ground  water  has  nothing  to 
do  with  the  alkali  accumulation.  Soils  are  frequently 
found  containing  a  medium  quantity  of  salt  distributed 
through  considerable  depth.  With  the  introduction  of 
irrigation  and  a  consequent  raising  of  the  water-table  to 
within  a  few  feet  of  the  surface,  an  ideal  condition  is  pro- 
vided for  a  concentration  of  these  diffused  salts  at  the 
surface.  This  may  render  entirely  unproductive  a  soil 
that  previously  raised  good  crops.  A  thorough  knowledge 
of  ground-water  conditions  is,  therefore,  important  be- 
fore a  person  is  able  to  make  an  intelligent  judgment  re- 
garding alkali  land. 

Analysis  of  the  Soil.  —  It  is  impossible  to  get  an  adequate 
idea  of  alkali  land  without  having  a  chemical  analysis  of 
its  water-soluble  material.  As  has  already  been  explained, 
a  superficial  examination  may  be  somewhat  deceiving, 
and  it  is  necessary  to  know  the  nature  and  concentration 
of  the  salts  to  considerable  depth  before  being  able  to  tell 
definitely  how  the  soil  will  act  and  whether  or  not  the  alkali 
is  likely  to  cause  trouble.  The  depth  to  which  the  soil 


244  JUDGING  ALKALI  LAND 

should  be  analyzed  depends  on  a  number  of  factors.  Four 
and  6  feet  are  often  taken  as  standards  but  id  feet  is 
better.  At  least  an  occasional  sample  should  be  taken  to 
this  depth  to  see  that  in  the  deep  subsoil  there  is  not  a 
layer  of  high  concentration  that  will  cause  trouble  later. 

The  exact  determinations  to  be  made  will  depend  on 
the  thoroughness  of  the  investigation  desired.  A  complete 
chemical  analysis  of  all  the  water-soluble  material  would 
be  desirable,  but  a  fair  idea  can  be  had  with  much  less 
work.  An  absolutely  necessary  determination  to  any  sort 
of  intelligent  diagnosis  would  include  total  soluble  salts, 
chlorides,  carbonates,  and  sulphates.  In  comparatively 
few  regions  where  nitrates  are  high,  they  should  also  be 
determined.  Where  any  large  part  of  the  sulphates  are 
calcium  sulphate,  calcium  should  be  determined  in  order 
that  the  calcium  sulphate  may  be  subtracted  from  the  total 
soluble  salts  and  the  sulphates.  Calcium  sulphate  is  not 
sufficiently  soluble  in  the  soil  solution  to  be  toxic  to  vege- 
tation, but  where  comparatively  large  quantities  of  water 
are  used  in  extracting  the  soil  for  analysis,  considerable 
calcium  sulphate  is  contained  in  the  solution,  and  where  it 
forms  any  large  part  of  the  dissolved  material  it  should  be 
taken  into  consideration.  It  is'  also  desirable  to  have 
determinations  made  of  other  bases  such  as  magnesium 
and  sodium,  but  these  determinations  are  not  so  valuable 
as  the  others  that  have  been  mentioned. 

The  methods  of  analysis,  particularly  the  method  of 
making  extractions,  must  be  taken  into  consideration  in 
interpreting  the  results.  Different  methods  give  different 
results;  consequently  the  methods  should  always  be  known. 
Details  of  the  various  methods  are  given  in  Chapter  VII. 

Possibility  of  Reclamation.  —  The  value  of  alkali  land 
is  affected  very  materially  by  the  possibility  and  the  ex- 


ECONOMIC   FACTORS  245 

pense  of  reclaiming  it.  Some  alkali  lands  are  so  situated 
that  reclamation  is  practically  impossible  or  would  be 
so  expensive  as  to  be  prohibitive.  Very  flat  land  that 
does  not  have  an  outlet  for  drainage  is  difficult  to  reclaim. 
Land  that  is  so  heavy  that  drainage  water  percolates 
slowly  has  its  salts  washed  out  with  difficulty.  Some  lands 
have  a  good  slope  and  the  soil  has  a  texture  suitable  for 
drainage,  but  there  is  no  available  supply  of  water  to  aid 
in  the  process  of  reclamation;  hence,  drainage  is  useless. 
It  is  apparent,  therefore,  that  not  only  the  quality  of  the 
soil  itself  must  be  taken  into  account,  but  also  the  condi- 
tions.  associated  with  its  reclamation. 

Economic  Factors.  —  Physical  features  of  the  soil  must 
be  used  in  connection  with  a  number  of  economic  factors 
in  judging  an  alkali  soil.  The  soil  has  no  particular  value 
aside  from  the  economic  returns  it  will  yield.  These 
depend  not  alone  on  actual  crop  yields,  but  also  on  cost 
of  production,  market  conditions,  and  a  number  of  other 
factors.  Distance  from  market  and  from  suitable  farm 
help  may  make  it  unprofitable  to  cultivate  even  a  fertile 
soil,  much  less  a  soil  the  productivity  of  which  is  decreased 
by  any  unfavorable  condition  such  as  the  presence  of  alkali. 
Climatic  conditions  may  not  be  such  as  to  make  possible 
the  raising  of  profitable  crops  that  are  resistant  to  alkali. 
A  soil  of  a  given  alkali  content  might  be  suitable  for  agri- 
culture in  a  region  where  date  palms  could  be  produced 
at  a  profit  and  yet  be  entirely  worthless  for  the  crops  of 
the  temperate  zone.  It  is  evident,  therefore,  that  alkali 
soil  of  any  particular  type  or  composition  cannot  be  said 
to  be  suitable  for  agriculture  without  taking  into  con- 
sideration numerous  conditions  other  than  those  associated 
with  its  merely  physical  features. 

The  demand  for  an  increased  acreage  of  land  to  supply 


246  JUDGING  ALKALI   LAND 

food  for  the  world  will  make  it  necessary  to  use  more  and 
more  the  lands  that  were  previously  not  considered 
worthy  of  cultivation.  This  will  demand  that  greater 
attention  be  given  to  alkali  lands,  and  that  more  intelligence 
be  put  into  understanding  and  reclaiming  them. 


INDEX 


Absorption  of: 

salts  by  soils,  109 

water,  34 
Abyssinian  highland,  source  of  soil, 

ii 

Acid,  sulphuric,  beneficial,  116 
Action,  mass,  106 
Advantages  of  drainage,  167 
Afghanistan,  alkali  in,  13 
Africa,  alkali  in,  10 
Alberta,  alkali  in,  7,  8 
Aldajem,  R.,  28,  32 
Alexandria,  rainfall  of ,  1 1 
Alfalfa,  197 
Algeria,  alkali  in,  10 
All,  B.,  103,  134,  139 
Alkali: 

black,  formation  of,  108 

-heath,  as  alkali  indicator,  63, 
69 

-indicating    plants,    description 
of,  74 

-loving  plants,  63 

meadow-grass,  206 

meadow-grass,    as    alkali    indi- 
cator, 64 

movement,  rate  of,  148 

-resistant  crops  in  reclamation, 
162 

salts,  antagonism  between,  113 

waters,  composition  of,  231,  232 

water  for  irrigation,  224 
Almond,  220 
America,  alkali  in,  6 


American  cowslip,  as  alkali  indicator, 

64 

Ames,  J.  W.,  14 

Ammonification,  effect  of  salts,  138 

Analysis: 

by  biological  method,  103 
by  freezing-point  method,  102 
of  Egyptian  soil,  12 
of  soil  in  judging  land,  243 

Analytical  methods,  comparison  of, 

85 

Analytical  process,  90 

Antagonism,  105 

between  alkali  salts,  113,  138 
noted  in  soil  bacteria  work,  116 

Ancient  seas  as  source  of  salts,  22 

Appearance  in  judging  land,  242 

Apple,  220 

Apricot,  220 

Arabia,  alkali  in,  13 

Area  affected  with  alkali,  4 

Argentina,  alkali  in,  10 

Aridity  necessary  for  alkali,  6 

Arizona,  alkali  in,  8 

Arizona  method  of  alkali  analysis, 
84,85 

Arrow: 

grass,  as  alkali  indicator,  64 
weed,  as  alkali  indicator,  63,  73 

Asia,  alkali  in,  13 

Asparagus,  217 

Aster,  as  alkali  indicator,  64 

Atrcplex,  as  alkali  indicator,  63,  70 

Atti,  R.,  14 

Australia,  alkali  in,  14 

Australian  salt-bush,  207 


247 


248 


INDEX 


B 

Bacterial    activities    increased    by 
drainage,  169 

Baluchistan,  alkali  in,  13 

Bancroft,  R.  L.,  14,  57,  58 

Barley,  212 

Barnes,  J.  H.,  103,  134,  139 

Barnyard  grass,  208 

Bases,  determination  of,  92 

Bates,  P.  H.,  190,  191 

Beam,  W.,  102,  103 

Becker,  A.,  120,  131 

Beeson,  J.  L.,  149,  151 

Bemmeln,  J.  M.  von,  121,  130 

Bicarbonates,  determination  of,  86 

Biological: 

activity,  toxic  limits  for,  135 
conditions  and  alkali,  132 
inactivity  and  soil  sterility,  133 
method  of  analysis,  103 

Birdsfoot  clover,  200 

Black  alkali: 

formation  of,  108 
neutralizing,  160 

Bluegrass,  203 

Blue-stem  grass,  206 

Bombay  Presidency,  alkali  in,  13 

Borates,  effect  on  capillarity,  128 

Bordign,  O.,  238 

Bouyoucos,  G.  J.,  102,  103 

Breazeale,  J.  F.,  29,  32,  40,  50.  54, 
58,  59,  117,  130,  160,  166 

Brazil,  alkali  in,  10 

Bridge  method,  94 

Briggs,  L.  J.,  80,  128,  129,  130,  131, 

144,  151 

British  Columbia,  alkali  in,  7 
Brome  grass,  202 
Brown,  C.  F.,  166,  174,  190 
Brown,  P.  E.,  15,  103,  136,  138,  139 
Bryan,  H.,  104 

Bud-brush,  as  alkali  indicator,  64 
Buffum,  B.  C.,  45,  51,  54,  58 


Bulrush,  208 

as  alkali  indicator,  64 

Burd,  J.  S.,  14 

Bureau  of  Soils  publications,  9 

Bureau  of  Standards  work  on  ce- 
ment, 176 

Burgess,  P.  S.,  118,  139 

Burke,  E.,  174,  190 

Bushy  samphir,  as  alkali  indicator. 
63,  66 

Butt,  N.  L,  151,  237 

Buttercup,  as  alkali  indicator,  64 


Cairo,  rainfall  of,  no 
Calcium: 

carbonate  hardpan,  124 

chloride,  solubility,  105 

determination  of,  92 

effect  on  salts,  116 

sulphate  antagonistic  with  so- 
dium sulphate,   115 

sulphate,  solubility,  105 
Caldwell,  J.  S.,  116,  117 
California: 

alkali  in,  8,  9 

method  of  alkali  analysis,  84,  85 

sodium    sulphate    experiments, 

108 

Cameron,  F.  K.,  20,  22,  28,  32,  44, 
46,  104,  113,  118,   124,  131, 

150,  151 

Camphor  tree,  221 

Canada,  alkali  in,  7 

Canadian  soils,  114 

Canal  lining,  32 

Capillarity  affected  by  alkali,  128 

Carbonates: 

determination  of,  86 
effect  on  capillarity,  128 
source  of,  28 

Carrying  capacity  of  drains,  180 

Carter,  E.  G.,  136,  139 


INDEX 


249 


Catlin,  C.  N.,  104 
Cause  of  hardpan,  123 
Celery,  217 
Cell: 

effect  of  alkali  on,  35 

sap  concentration,  35 
Cement  drain  tile,  1 74 
Changing  soil  structure,  119 
Chemical: 

equilibrium,  105 

methods  of  determining  alkali,  81 

treatments  for  alkali,  161 
Chezy-Kutter  formula,  179 
Chili,  soluble  salt  deposits  in,  10 
Chloride: 

determination,  88 

effect  on  capillarity,  130 
Clarke,  F.  W.,  14,  18,  20,  32 
Clovers,  200 
Code,  W.  W.,  238 
Coe,  H.  S.,  199,  221 
Colloids,  effect  of  alkali  on,  122 
Colorado,  alkali  in,  8,  9 
Comparison  of  analytical  methods, 

85 . 
Composition  of: 

alkali  in  judging  land,  243 

alkali  waters,  231,  232 

earth's  crust,  18 

hardpan,  127 

lithosphere,  17 

ocean  water,  18 

rocks,  1 6,  17 

soil-forming  minerals,  17 
Conner,  S.  D.,  221 
Construction  methods,  183 
Contamination : 

source  of,  154 

of  irrigation  water,  225 
Copper,  effect  on  salts,  116 
Corn,  214 

Cost  of  drainage,  189 
Cotton,  218 


Cotton  wood,  221 
Coupin,  H.,  46,  48,  58 
Cowslip;  as  alkali  indicator,  64 
Crawley,  J.  T.,  238 
Crepis,  as  alkali  indicator,  64 
Cressa,  as  alkali  indicator,  63,  70 
Cretacious  deposits,  23 
Crimson  clover,  200 
Cropping  in  reclamation,  162 
Crops  for  alkali  land,  192 
Crust,  effect  on  evaporation,  157 
Cultivation  to  reduce  evaporation, 
154 


Dakota  formation.  23,  24 

Date  palms,  219 

Davis,  R.  O.  E.,  104,  121,  128,  131 

Davy,  J.  B.,  60,  80 

Deakin,  A.,  14 

Decomposition  of  rocks,  19 

Deflocculation  of  soil  by  alkali,  121 

De  Greef,  H.,  220 

Demoussy,  E.,  118 

Description      of      alkali-indicating 

plants,  74 

Desolation,  caused  by  alkali,  3 
Determination  of: 

alkali,  81 

bases,  92 

bicarbo nates,  86 

calcium,  92 

carbonates,  86 

chloride,  88 

magnesium,  93 

nitrate,  89 

sodium,  93 

sulphaie,  89 

total  solids,  86 

Determining  need  of  drainage,  170 
Dieckman,  G.  P.,  176,  190 
Dimo,  N.  A.,  15,  146,  151 
Dissolved  matter  washed  to  sea,  19 


250 


INDEX 


Distribution  of  alkali,  6 

Dorscy,  C.  W.,  20,  32,  147,  148,  151, 

166,  221,  238 
Drain  outlets,  188 
Drainage: 

advantages  of,  167,  169 

cost  of,  189 

for  reclamation  162,  167 

machines,  186,  187 
Drains: 

carrying  capacity  of,  180 

size  of,  178 

types  of,  171  ^ 
Duggar,  B.  M.,  40 
Dwarf  samphir,  as  alkali  indicator, 

63,66 

Dymond,  T.  S.,  213,  221 
Dynamite  in  breaking  hardpan,  123 


Earth's  crust,  composition  of,  18 
Eaton,  F.  M.,  239 
Eckart,  C.  F.,  221,  238 
Economic  factor  in: 
crop  choice,  195 
judging  land,  243 
Effect  of: 

alkali  on: 

ammonification,  138 
bacteria,  132 
capillarity,  128 
colloids,  122 
germination,  36 
nitrogen  fixation,  137 
plant  structure,  38 
soil  tilth,  120 
surface  tension,  128 
salts  on: 

evaporation,  130 
moisture  movement,  128 
soil  organisms  on  sterility,  133 
water-table,  145 
Egypt,  alkali  in,  10,  IT  , 


Egyptian: 

clover,  200 

millet,  208 

Electric  bridge  method,  94 
Emmer,  214 
English  rye  grass,  204 
Equilibrium: 

chemical,  105 

in  soil  solution,  in 
Eucalyptus,  220 
Europe,  alkali  in,  13 
Evaporation : 

of  moisture,  130 

of  saline  lakes,  27 

reduction  of,  155 
Experiments: 

in  loam,  53 

in  sand,  49 

with  rice,  114 

with  sodium  sulphate  in  Calif., 

108 
Extract  of  soil,  81 


Factors  affecting  resistance,  192 

Failyer,  G.  H.,  82,  104 

False  golden  rod,  as  alkali  indicator. 

73 

Fescue,  204 
Fiber  crops,  218 
Field  peas,  200 
Flax,  218 
Flocculation  of  soil,  effect  of  alkali, 

121 
Flooding  to  reclaim  land  in  Egypt, 

1 60 

Forage  crops,  197 
Forbes,  R.  H.,  229,  238 
Formation  of: 

black  alkali,  108 

carbonates,  28 

hardpan,  123 

nitrates,  30 


INDEX 


251 


Formation  of: 

sodium  bicarbonate,  106 
Formula  for  Mass  Action,  106 
Fowler,  T.  W.,  134,  139 
Fraps,  G.  S.,  237,  238 
Freak,  G.  A.,  102,  103 
Free,  E.  E.,  121, 131 
Freezing-point  method   of  analysis, 

102 

Fruit  trees,  219 
Fulaykov,  N.,  238 
Fungi  in  soil  and  fertility,  133 


Gandechon,  II. ,  152 

Gardner,  F.  D.,  123,  124,  131,  197, 

^238 

Gedroits,  K..  K.,  22,  29,  32,  131 
Geographical  distribution  of  alkali,  6 
Geology  in  judging  land,  240 
Gericke,  W.  F.,  115,  118, 
Germination: 

effect  of  alkali  on,  36 

experiments,  44 
Giant  rye-grass,  207 
Gila  River  water,  225 
Glaux,  as  alkali  indicator,  64 
Golden  willow,  221 
Goldthorpe,  H.  C.,  136,  139 
Grade  of  drain,  177 
Goose  foot,  as  alkali  indicator,  64 
Grain  crops,  210 
Grapes,  220 
Grasses,  200 

Greasewood,  as  alkali  indicator,  63, 68 
Great  Basin,  alkali  in,  8 
Greaves,  J.  E.,  22,  33,  91,  103,  104, 

136,  138,  139,  238 
Green  River  formation,  27 
Guthrie,  F.  B.,  55,  56,  58,  229,  238 
Gypsum: 

for  black  alkali,  160 

leaching  of,  129 


H 

Hall,  A.  D.,  120, 131 
Hansen,  D.,  142,  151,  222 
Hansteen,  B.,  48,  58,  117 
Hardpan,  122 

Hare,  R.  F.,  84,  104,  150,  151 
Harris,  F.  S.,  32, 40,  53,  58,  118, 130, 
131,  isr,  152,  158,  166,  203, 

222,  237 

Hart,  R.  A.,  165,  166, 174,  179,  189, 

190 

Harter,  L.  L.,  38,  40,  59 
Haselhoff,  E.,  48,  54,  58 
Headden,W.  P.,  32,  57, 142, 145, 146, 

152,  161,  166,  176,  190,  211, 

215,    222,    238 

Headley,  F.  B.,  222 

Hebert,  A.,  15 

Hecke,  E.,  220,  222 

Heime,  C.,  220 

Heileman,  W.  H.,  127,  131 

Helms,  R.,  55,  56,  58 

Hicks,  G.  H.,  40,  46,  58 

Hilgard,  E.  W.,  9,  15,  32,  40,  69,  80, 
121,  123,  131,  144,  147,  152, 
158,  160,  166,  197,  207,  217, 

222,    229,    238 

Hill,  E.  G.,  15 
Hills,  T.  L.,  137,  139 
Hirst,  C.  T.,  91,  104,  238,  239 
Hissink,  D.  J.,  152 
Hitchcock,  E.  B.,  136,  139 
Holmes,  J.  G.,  212,  222 
Houston,  D.,  213,  221 
Hungary,  alkali  in,  13 


Imperial  Valley,  alkali,  in,  8 
Inactivity    of    organisms    and    soil 

sterility,  133 
India,  alkali  in,  13 
Indicating  plants,  description  of,  74 
Indicator  value  of  vegetation,  6g 


252 


INDEX 


Injury,  nature  of,  34 

Inkweed,  as  alkali  indicator,  63,  65 

Irrigation: 

systems  in  Egypt,  12 

water,  224 

water,  carrier  of  alkali,  30 

water,  composition  of,  231,  232 

water,  toxic  limits,  228 

weed,  as  alkali  indicator,  63,  73 

Isham,  R.  M.,  30,  33 

Italian  rye  grass,  204 

Italy,  alkali  in,  13 


Japanese  wheat  grass,  203 

Jeffery,  J.  A.,  190 

Jensen,  C.  A.,  80,  211,  212,  215,  222, 

239 

Joffa,  M.  B.,  118 
Johnson,  D.  R.,  .138,  139 
Jost,  L.,  40 

Judging  alkali  land,  240 
Jurassic  deposits,  23 

K 

Kearney,  T.  H.,  15,  39,  40,  44,  46, 
47,  58,  59,  80,  113,  118,  197, 

199,  200,  201,  202,  203,  204 
205,  208,  210,  212,  213,  214, 
217,  2l8,  221,  222 

Kellerman,  K.  F.,  122,  131 
Kelley,  W.  P.,  29,  32,  118,  135,  137, 

139 

Kern   greasewood,    as    alkali    indi- 
cator, 63,  66 

King,  F.  H.,  82, 146,  152,  190 

Klein,  M.  A.,  139 

Knight,  W.  C.,  32,  118 

Knop's  solution,  43 

Kochia,  as  alkali  indicator,  63,  72 

Kolotov,  G.  I.,  152 

Kolreuteria,  220 


Kossovich,  P.,  59,  144,  152,  238 
Kravkov,  S.,  152 
Kuiiper,  J.,  239 


Lakes,  saline,  27 
Land: 

judging,  240 

method  of  reclaiming,  154 
Lapman,  M.  H.,  128,  129,  144,  151 
Law  of  Mass  Action,  106 
Laying  out  system,  177 
Leaching  of  gypsum,  129 
Leather,  J.  W.,  14,  15 
Leaves  to  reduce  evaporation,  157 
Le  Clerc,  J.  A.,  43,  50,  54,  59,  117 
Legumes,  200 
Lemon,  220 
Lcsage,  P.,  59 

Lime,  corrective  for  magnesium,  114 
Limestone,  composition  of,  17 
Lining  of  canals,  32 
Limit  of  biological  activity,  135 
Limits,  toxic,  42 
Linsley,  J.  D.,  166 
Lipman,  C.  B.,  103,  115,  118,  134, 

135,  137,  139,  161,  166 
Lippincott,  J.  B.,  239 
Lithosphere,  composition  of,  17 
Little  rabbit  brush,  as  alkali  indica- 
tor, 63,  73 

Loam,  experiments  in,  53 
Loughbridge,  R.  H.,  121,  131,  147, 
152,  160,  166,  200,  201,  203, 

204,    206,    208,    209,    211,    212, 
214,    217,    222 

Lumber  drains,  180,  184 

M 
Mackie,  W.  W.,  80,  142,  145,  147, 

152,  212,  229,  239 
MacOwan,  P.,  15 


INDEX 


253 


Magnesium: 

determination  of,  93 

chloride,  solubility,  105 

corrected  by  lime,  114 

sulphate,  solubility,  105 
Magowan,  Florence  N.,  44,  59 
Mancos  shale,  24,  25,  26,  27 
Manhole  for  drain,  189 
Mann,  H.  H.,  15 
Marchal,  E.,  48,  59,  140 
Marquenne,  L.,  118 
Marsh  grass,  as  alkali  indicator,  64 
Masoni,  G.,  121,  131 
Mass  Action,  106 

McCool,  M.  M.,  102,  103,  142,  152 
McLane,  J.  W.,  80 
Mead,  C.  E.,  222 
Meade,  R.  K.,  175,  190 
Meadow  fescue,  204 
Meaning  of  alkali,  5 
Means,  T.  H.,  12, 15,  18,  22,  33,  160, 

166, 197,  239 
Merrill,  G.  P.,  18 
Mesopotamia,  alkali  in,  13 
Method: 

electric  bridge,  94 

of  reclaiming  alkali  land,  154 
Methods: 

comparison  of,  85 

of  constructing  drains,  183 

of  determining  alkali,  81 
Micheels,  H.,  40,  45,  59 
Microorganisms,  effect  of  alkali  on, 

132 

Miller,  C.  E.,  142,  152  . 
Millets,  208 
Minerals: 

alkali  in,  19 

in  rocks,  16 

Miyake,  K.,  59,  114,  118 
Montana: 

alkali  in,  9 

formation,  25 


Montana: 

method  of  alkali  analysis,  84,  85 
Moisture: 

evaporation,  130 

movements,  128 
Modiola,  206 
Morocco,  alkali  in,  10 
Mousetail,  as  a&ali  indicator,  6 
Movement  of: 

alkali  with  water,  142 

moisture,  128 

salt,  rate  of,  148 

soluble  salts,  141 

various  salts,  146 

Mulch  to  reduce  evaporation,  154 
Mulberry,  220 
Munter,  E.,  138 
Muntz,  A.,  152 
Myers,  H.  C.,  80 


N 
Native: 

grasses,  205 

vegetation  as  alkali  indicator, 
60,63 

vegetation  in  judging  land,  242 
Nature  of  alkali  injury,  34 
Need  of  drainage,  170 
Neill,  N.  P.,  199,  201,  222 
Nelson,  A.,  208,  222 
Neutralizing  sodium  carbonate,  160 
Newell,  F.  H.,  239 
Nile  River  Valley,  alkali  in,  n,  12 
Nitrate: 

determination,  89 

formation,  30 

Nitrates,  effect  on  capillarity,  129 
Nitric  acid  for  alkali  land,  161 
Nitrogen  fixation,  effect  of  salts  on, 

137 

North  America,  alkali  in,  6 
Nutrient  solutions,  43 


254 


INDEX 


Oat-grass,  204 
Oats,  213 
O'Brien,  D.,  239 
Ocean: 

as  source  of  alkali,  21 

water,  18 
Olives,  220 
Onions,  217 
Open  drain,  172 
Orange,  220 
Orchard: 

grass,  202 

killed  by  alkali,  39 
Organisms  and  soil  fertility,  132 
Origin  of: 

alkali,  16 

hardpan,  123 

Osterhout,  W.  J.  V.,  117,  118 
Otto,  R.,  239 

Oudh  Province,  alkali  in,  13 
Outlets,  1 88 


Pagnoul,  A.,  149,  152 

Parson,  J.  L.,  190 

Patten,  H.  E.,  150,  151,  152 

Peach,  220 

Pear,  220 

Peas,  200 

Peimersel,  R.  L.,  80 

Pepper  grass,  as  alkali  indicator,  64 

Persia,  alkali  in,  13 

Peterson,  Wm.,  22,  30,  33 

Pfeffer,  W.,  36,  41 

Phillips,  A.  J.,  190,  191 

Phosphates,  effect  on  capillarity,  128 

Physical  condition  of  soil,  119 

Pigweed,  as  alkali  indicator,  64 

Pinckney,  R.  M.,  174,  190 

Pittman,  D.  W.,  53,  104,  203,  222 

Plant  descriptions,  74 

Plants  as  indicators  of  alkali,  60,  63 


Plasmolysis  of  cell,  35 
Plowing  under  alkali,  158 
Plovvmans'  wort,  as  alkali  indicator, 

64 

Pomegranate,  221 
Poplars,  221 
Poncelet's  formula,  178 
Port  Said,  rainfall  of,  n 
Potatoes,  216 
Practical  drainage,  167 
Prairie  grass,  206 
Precipitation  records,  n 
Preliminary  survey,  176 
Preparing  solution  of  soil,  81 
Prevention  of  water  absorption,  34 
Proso  millet,  208 
Prune,  220 

Puchner,  II.,  144,  152 
Punjab,  alkali  in,  13 
Purple  top: 

as  alkali  indicator,  63 

grass,  206 
Pyrrocoma,  as  alkali  indicator,  64 


Quantity  of  salts  to  reduce  yields,  56 

R 

Rabbitt  brush,  as  alkali  indicator, 

63,  73 

Radishes,  217 
Rape,  209 

Rate  of  alkali  movement,  148 
Reclamation: 

by  cropping,  162 

methods,  154 

system  in  Egypt,  12 
Red  clover,  200 
Red  top,  203 

Reduced  yields  from  salts,  56 
Reducing  evaporation,  155 
Reh  commission,  13,  14 
Reh  lands,  13 


INDEX 


255 


Relation  of: 

alkali   to  biological  conditions, 
132 

alkali    to    physical    conditions, 

119 

Removing  salts  from  surface,  159 
Resistance: 

factors  affecting,  192 

tables,  96 

Resistant  crops  in  reclamation,  162 
Reviel,  59 

Rhodesia,  alkali  in,  10 
Rice,  214 

experiment  with,  114 
Robinson,  J.  S.,  130,  131,  151,  158, 

166 

Rock,  composition  of,  16 
Rolet,  A.,  160,  166 
Root: 

crops,  215 

zone  increased  by  drainage,  169 
Roots  injured  by  alkali,  34 
Rushes,  208 

Rush,  as  alkali  indicator,  64 
Russian  olive,  221 
Rye,  214 

grass,  204 


Sachsse,  R.,  120,  131 

Sackett,  W.  G.,  30,  33,  140 

Sage  brush  as  indicator  of  land,  242 

Sahara,  soils  of,  10 

Saline  lakes,  27 

Salt: 

bushes,  207 

ush  as  alkali  indicator,  63,  70 
.  crust,  relation  to  evaporation, 

157 

grass,  205 
grass,  as  alkali  indicator,  63,  73, 

243 
movement  with  water,  142 


Salt: 

River  water,  225 

wort,  as  alkali  indicator,  63. 

Salts: 

absorption  by  soils,  109 
antagonism  between,  113 
by  bridge  method,  94 
by  freezing-point  method,  102 
effected    by    calcium,    copper, 

zinc,   116 

effect  of,   on   moisture  move- 
ment, 128 

from  ancient  seas,  22 
in  hardpan,  127 
in  natural  soil,  141 
movement  of,  14,  146 
plowing  under  of,  158 
quantity  to  reduce  yields,  56 
removal  from  surface,  159 
removed  in  drainage,  163,  164 
soluble  in  water,  105 
solubility  of,  106 

Samphire,  as  alkali  indicator,  63 

Sanchez,  A.  M.,  198,  222 

Sand,  experiments  in,  49 

Sandsten,  E.  P.,  166 

Sandstone,  composition  of,  16,  18 

Saskatchewan,  alkali  in,  7 

San  Joaquin  Valley,  alkali  in,  8 

Schreiner,  O.,  82,  104 

Scofield,  C.  S.,  239 

Sedger,  208 

Seed  germination  experiments,  44 

Shading  to  reduce  evaporation,  157, 
158 

Shadscale,  as  alkali  indicator,  63,  70 

Shale,  composition  of,  16,  17 

Shantz,  H.  L.,  80 

Sharp,  L.  T.,  115,  118,  131,  137,  148, 

*49,  153 
Shaw,  G.  W.,  15 
Shinn,  C.  H.,  152,  160,  166 
Shooting  star,  as  alkali  indicator,  64 


256 


INDEX 


Shrubs,  218,  219 

Shutt,  F.  T.,  8,  15,  54,  59,  118,  204, 

206,  211,  212,  217,  223 

Sigmond,  A.,  von,  15,  45,  59 

Silt  basins,  188 

Sims,  C.  E.,  90,  176 

Size  of  drains,  178,  181,  182 

Skinner,  W.  W.,  104 

Slossom,  E.  C.,  32,  40,  45,   51,  59, 

239 

Smith,  E.  A.,  15,  206,  211,  223 
Smith,  J.  G.,  222 
Snow,  F.  J.,  15 
Sodium: 

determination  of,  93 
bicarbonate,  formation  of,  106 
carbonate: 

hardpan, 127 
neutralizing  of,  160 
solubility,  105 
chloride,  solubility,  105 
nitrate,  solubility,  105 
sulphate,  experiments  in  Cali- 
fornia, 108 

sulphate,  solubility,  105 
Soil: 

analysis  of,  12 

bacteria,    antagonistic    results 

with,  116 
composition    in    judging  land, 

243 

extract,  81 

fertility  and  organisms,  132 
indicated  by  plants,  60 
movement  of  alkali  through,  141 
organisms  and  fertility,  132 
physical  condition  of,  119 
solution,  equilibrium  in,  in 
solution,  preparation  of,  81 
solution,  variance  in  concentra- 
tion, 112 

warmed  by  drainage,  169 
sterility  and  organisms,  133 


Soils: 

absorption  of  salts,  109 

Canadian,  114 
Solids,  determination  of,  86 
Soluble: 

salt  movement  with  water,  142 

salts,  movement  of,  141 

salts  by  bridge,  94 

salts  in  hardpan,  127 
Solubility: 

affected  by  temperature,   105, 
109,  112 

of  salts,  105,  1 06 
Solution: 

experiments,  44 

Knop's,  43 

nutrient,  43 

preparation  of,  81 
Solutions: 

alkali,  44 

nutrient,  43 

toxicity  of,  43 
Sorghums,  208 
Source  of: 

alkali  determines  methods,  154 

contamination,  154 
Sources  of  water  contamination,  225 
South  Africa,  alkali  in,  10 
South  America,  alkali  in,  10 
Spike  weed,  as  alkali  indicator,  63, 

73 

Stabler,  H.,  239 

Strahorn,  A.  T.,  80,  211,  215,  239 
Steik,  K.,  176,  190 
Stevenson,  W.  H.,  15 
Stewart,  J.,  51,  123,  124 
Stewart,  R.,  22,  30,  33,  104,  239 
Straw  to  reduce  evaporation,  15? 
Structure  of: 

plants  affected  by  alkali,  38 

soil,  119 
Sugar-beets,  215 
Sulphate  determination,  89 


INDEX 


257 


Sulphuric  acid: 

beneficial,  116 

treatment  for  alkali,  161 
Sunflowers,  214 
Surface: 

removal  of  salts  from,  159 

tension     affected     by     alkali, 

128 

Survey  for  drains,  176 
Swan  tract,  reclamation  of,  162 
Sweet  clover,  199 
Sycamore,  220 
Symmonds,  R.  S.,  161,  166 
Szik  lands,  13 


Table  of  solubility  of  salts,  105 
Tables  of  electrical  resistance,  96 
Tall  meadow  oat-grass,  204 
Tamarisk,  221 
Tamhane,  V.  A.,  15 
Taylor,  C.  S.,  133,  140 
Temperature,   effect    on   salt   solu- 
bility, 105,  109,  112 
Tertiary  formation,  26,  27 
Texas  method  of  alkali  analysis,  84, 

85 

Tilth  of  soil,  effect  of  alkali  on,  120 
Timothy,   202 
Tolerance  of  various  crops  to  alkali, 

196 

Torpedo  drain,  173 
Total  solids,  determination  of,  86 
Tottingham,  W.  E.,  44,  59,  222 
Toxicity  of: 

salts  alone,  43 

solutions,   43 
Toxic  limits: 

for  bacteria,  135 

of  alkali,  42 

Trailing  buttercup,  as  alkali  indi- 
cator, 64 
Transpiration  reduced  by  salts,  34 


Traphagen,  F.  W.,  15,  22,  33,  202, 

212,  213,  222 
Treatment    of    alkali    affected    by 

origin,  31 

Treatments  for  alkali,  chemical,  161 
Trees,  218 
Treitz,  P.,  29,  33 
True,  R.  H.,  41,  48,  59 
Tuber  bulrush,  64 
Tulaykov,  N.,  15,  143,  153 
Tunis,  alkali  in,  10 
Turkestan,  alkali  in,  13 
Tussock  grass,  206 

as  alkali  indicator,  63,  65 
Types  of  drains,  171 

U 

United  States,  alkali  in,  8 
Usar  lands,  13,  14 
Utah: 

alkali  in,  8 

method  of  alkali  analysis,  84,  85 


Valeria,  as  alkali  indicator,  64 
Van  Winkle,  W.,  239 
Vapor  tension  reduced  by  salts,  130 
Variance  of  soil  solution  concentra- 
tion, 112 
Variation  in  composition  of  water, 

234 

Vegetables,  215 

Vegetation  as  alkali  indicator,  60,  63 
Vetch,  200 
Vinson,  A.  E.,  104 
Vissotski,  G.,  15 
Vreis,  H.  de,  36,  44 

W 

Waggaman,  W.  H.,  152 
Warington,  R.,  146,  148,  153 
Washington,  alkali  in,  9 
Washingtonia  palm,  221 


258 


INDEX 


Water: 

absorption,  prevention  of,  34 

composition  of,  231,  232 

for  irrigation,  224 

from  Gila  River,  225 

from  Salt  River,  225 

from  various  rivers,  226,  227, 
228 

supply  increased  by  drainage, 
169 

-table,  effect  of,  145 

-table,  effect  of  on  evaporation, 
158 

-table  in  judging  land,  243 

toxic  limits,  228 
Weed,  H.  H.,  22 
Weir,  W.  W.,  166,  188,  191 
Western  wheat  grass,  203 


Wheat,  210 

White  sage,  as  alkali  indicator,  63,  72 

Whitney,  M.,  18,  22,  33 

Widtsoe,  J.  A.,  239 

Wig,  R.  J.,  190,  191 

Wild  grasses,  205 

Wiley,  H.  W.,  104 

Willcocks,  W.,  15,  191,  239 

Wohltman,  F.,  239 

Wyoming,  alkali  in,  8* 


Yields  reduced  by  salts,  56 
Yohe,  H.  S.,  191 


Zinc,  effect  on  salts,  116 


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OCT22   1947 


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